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﻿Title: The Barnet Book of Photography - A Collection of Practical Articles
Author: Various
Language: English
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THE BARNET
BOOK OF
PHOTOGRAPHY.
THE BARNET
BOOK OF
PHOTOGRAPHY.
A COLLECTION OF PRACTICAL ARTICLES
BY
CAPT. W. DE W. ABNEY, C.B., F.R.S., ETC.
CHARLES H. BOTHAMLEY, F.C.S., F.I.C.
CHAPMAN JONES, F.C.S., F.I.C.
HAROLD BAKER
A. HORSLEY HINTON
JOHN H. AVERY
W. THOMAS
ANDREW PRINGLE
JOHN A. HODGES, F.R.P.S.
REV. F. C. LAMBERT, M.A.
W. ETHELBERT HENRY, C.E.
JAMES PACKHAM, F.R.P.S.
THO'S. S. SKELTON
[Illustration]
THIRD EDITION.
Published by
ELLIOTT & SON, BARNET, HERTS.
PERCY LUND, HUMPHRIES & CO., LTD.,
3, AMEN CORNER, LONDON, E.C.
1898.
[Illustration]
CONTENTS OF
THE BOOK.
PAGE.
ALPINE PHOTOGRAPHY. _W. de W. Abney, C.B., F.R.S._ 9
NEGATIVE MAKING. _C. H. Bothamley, F.C.S., F.I.C._ 23
LENSES. _Chapman Jones, F.C.S., F.I.C._ 57
PORTRAITURE. _Harold Baker_ 77
PICTORIAL PHOTOGRAPHY. _A. Horsley Hinton_ 87
ARCHITECTURAL PHOTOGRAPHY. _John H. Avery_ 117
THE HAND CAMERA AND ITS USE. _W. Thomas_ 131
LANTERN SLIDES. _Andrew Pringle_ 141
HOW TO MAKE ENLARGEMENTS. _John A. Hodges, F.R.P.S._ 155
P.O.P. _Rev. F. C. Lambert, M.A._ 177
PLATINOTYPE PRINTING. _A. Horsley Hinton_ 197
CONTACT PRINTING ON BROMIDE PAPER. _W. Ethelbert Henry, C.E._ 225
THE GUM-BICHROMATE PROCESS. _Jas. Packham, F.R.P.S._ 241
AN INTRODUCTION TO CARBON PRINTING FOR BEGINNERS 253
THE CARBON PROCESS. _Thomas S. Skelton_ 261
ILLUSTRATIONS.
HOMEWARDS. KARL GREGER 16
AMONG THE ALPS. W. DE W. ABNEY 24
WINTER TIME ON THE ALPS. W. DE W. ABNEY 40
MELTON MEADOWS. A. HORSLEY HINTON 72
MISS LILY HANBURY--A PORTRAIT. HAROLD BAKER 88
GATHER THE ROSES WHILE YE MAY. ALEX. KEIGHLEY 120
BIRCH AND BRACKEN. W. THOMAS 136
DRIFTING STORM CLOUDS. W. THOMAS 168
STREONSALCH. W. J. WARREN 200
CUPBOARD LOVE. T. LEE SYMS 232
AT THE FOUNTAIN. J. W. WADE 264
PREFACE.
[Illustration: THE BARNET BOOK OF PHOTOGRAPHY.]
_The purpose of this book is to place in the hands of every
Photographer instructive articles on essential processes and
manipulations, by eminent writers who have given such subjects their
especial study, and who have borne in mind that whilst the
experienced Amateur and the Professional may each find much to learn
from a comparatively elementary description of methods and means, it
is the Beginner who stands in greatest need of help._
_In the mind of every photographer the name of Barnet is inseparable
from a great Photographic Industry, and now it is intended that the
name shall be associated with a good and useful book, which is
called the_ BARNET BOOK OF PHOTOGRAPHY, _and it is left to the
reader to say if the fulfilment of its purpose and the manner of its
doing are such as to justify its existence._
_To all who are interested in photography, who love it for itself
and for its productions, and who desire to improve their own
practice of its many processes and applications, this Book is
respectfully dedicated._
_Barnet, Herts._
_April, 1898._
_ELLIOTT & SON._
[Illustration: COPYRIGHT. NEGATIVE BY W. L. F. WASTELL. A FAMOUS
PIKE STREAM. Contact Print on BARNET PLATINO-MATT BROMIDE PAPER.]
_Alpine Photography._
[Illustration]
Writing in London on a day in winter with a murky sky and sloshy
streets, the title of Alpine Photography is verily refreshing. It
brings back days of sunlight and joyous experiment, and as we write
the soul stirring scenery is before us called up by photographs
taken under varying conditions of comfort and discomfort. That there
is something different in Alpine photography to photography in our
own country, we are bound to believe, since a special article is
demanded for it.
The first question invariably asked is as to the nature of the outfit
required. We should here like to divide our reply into two divisions.
The one concerning the mountaineer, and the other the ordinary
tourist. For the former we have no doubt in our minds that a hand
camera to take 1/4 plate or 5 × 4 pictures is the most convenient
form of camera to take. It is not our business to advertise any
person's wares and we shall content ourselves by saying that
personally we prefer a camera which has separate slides and does not
possess a magazine, more particularly when glass plates are to be
used, though a form of Kodak is not to be despised. But perhaps we
are prejudiced in favour of glass plates, for they are simple to
manipulate and have no cockles nor other drawbacks which the careless
photographer may have to encounter. Probably the most useful lens to
employ is a doublet of which the focal length is about a quarter more
than the width of the plate, since it includes a fair angle and the
margins of the photographs are not likely to be markedly different in
general density to the centre, as is the case when wide-angle lenses
are employed. In England a lens which will cover with a large stop,
say _f_/8, is a desideratum, but in the Alps it is very rarely that
such a large ratio of aperture to focal length is required. As a rule
for ordinary plates a lens has to be stopped down to _f_/16 to give a
negative in say 1/50th of a second. Nevertheless where orthochromatic
plates are to be employed it is very necessary to have a lens which
will cover a plate satisfactorily with _f_/8 in order to use a colour
screen for producing orthochromatic effects, since the loss of
photographic light caused by the screen can only be compensated for
by such an aperture even when the shutter is slowed down. The reader
is therefore recommended on the whole to furnish himself with one of
the modern lenses which work at _f_/8, though he must remember that
the larger the aperture employed the more the margins and centre of
the picture will suffer from unequal exposure. With some hand cameras
there is a means of attachment to a stand, but a stand on a mountain
is difficult to use and moreover has on more than one occasion been
proved dangerous to carry. The mountaineer if he desires to give a
time--and not an instantaneous--exposure on his excursion, would do
well to have a small clip ready to attach to the head of his ice axe.
The axe will form a sufficiently stable stand for the more prolonged,
but still short, exposure that he may be required to give on some
particular subjects such as a photograph at sunrise or near sunset.
Photographers in England are rarely afflicted with breathlessness
through exertion, but it is different in mountaineering. A
mountaineer may keep his wind, but it would be rare to find that his
heart was beating equably after some spurt of exertion, such as rock
climbing. It is often after some such exertion that he comes upon
some view which he may wish to record on his photographic plate. The
usual method of holding the hand camera would under such
circumstances prove a failure so far as sharpness of image is
concerned. Pressed against his "middle" or "upper" chest, the
beatings of the heart will record themselves on the photograph.
Under such circumstances resort must be had to some form of support
on which to rest his camera. After many years' experience, the
writer has come to the conclusion that there is no support superior
to the ice axe. It is not necessary to cause it to stand upright in
the ground, ice, or snow, though this should be done if possible. It
will suffice to rest the point on the rock, and place the camera on
the axe head, with the pick parallel to the body. We then have a
firm support in one direction, and the hands, which are not affected
by the automatic motion of the heart, can be trusted to keep it
steady in the other direction. Photographs taken with a good lens,
and with such a stand, will bear enlarging up to 22 inches, at
least. It is because these photographs will bear enlarging that a
small plate is recommended to the mountaineer. There is not a large
proportion of Alpine views taken on the mountain side of which one
would care to have anything but a memorandum, and it is such a size
as that recommended which gives such a memento, and which, if
desired, allows a more formidable size to be acquired at home, where
we may suppose there are all the conveniences that a photographic
laboratory affords. The writer has had experience on mountains with
cameras varying from 12 × 10 to the 1/4 plate size. When younger and
more inclined to waste a few valuable minutes of daylight in putting
up a camera stand, the 12 × 10 gave pictures which we often lamented
having taken, whilst in his more mature years, a snap-shot has never
been regretted. The cameras which require stands, require one porter
at least to carry them, for although the late Mr. Donkin carried his
own 7-1/2 × 5 camera up the highest peaks, it is few men, who, even
if they had the energy or the physique that he had, would imitate
his example. A porter means an extra expense in fees, and an extra
mouth to feed, and very likely entails slowness in a climb through
having an additional man upon the rope. A quarter plate or a 5 × 4
camera the owner, however, can himself carry; but the best form of
attaching it to his body has been a difficult task to evolve. Many
and many different attachments have been tried. One thing is quite
certain, and that is, the camera should be in a stout case, but it
cannot be carried over the shoulders by a strap as we can do in
comparatively level countries. Let anyone try to come down a rock
with the camera slung over his shoulders, and he will soon find it
dangling in front of his stomach, or swinging like a pendulum, and
threatening to displace him from what at best may be a treacherous
handhold. The method of attachment we adopt now, will be readily
seen from the diagram.
[Illustration]
The shoulder strap is utilized, but a ring is attached to the back
of the case as shown, and a strap or piece of whipcord comes over
the strap as shown. The two shoulders are in AA and the case is
carried as a knapsack. The length of the cord or strap BB is so
adjusted, as is also the length of the shoulder strap, that the
camera lies against the small of the back, and that it will not
swing away from the body. At one time the ring was placed in front
of the case, but the result was merely to cause the top of the case
to rest against the back. The plan shown above has answered under
almost every variety of circumstances, and the weight is
inconsiderable. (A friend has his camera attached to the bottom of a
small "rücksac" and this answers, but as the writer does not carry
his own provisions or change of garments he has not adopted this
plan). A long day's march may be undertaken if this contrivance be
employed, and the weight is scarcely felt.
For those who have not had extensive practice with hand cameras, a
view finder is, if not a necessity, at all events, a great help. On
the whole, perhaps the best form is that in which a miniature view
falls on a ground glass. It must be recollected, however, that each
view finder is adapted for some particular focal length of lens.
The view in the finder and on the plate should be compared, and if
the former is more extensive, the surplus ground glass should be
covered up with a black mask.
If it be determined to take a camera with its stand, very few
directions are required beyond those which apply to ordinary view
work on the plains. It may perhaps be as well to mention that a
camera stand placed on ice or snow, is not immovable until the iron
shoes of the legs attain the temperature of the surrounding snow or
ice. An exposure of a few seconds will often show an image which has
moved on the plate.
The next point that we may call attention to is the plate to be
employed. With a hand camera there is no absolute necessity to have
the most rapid plate, as far as exposure is concerned, but in
mountain work it must be recollected that there are very great
contrasts to represent on the print. "The slower the plate the
steeper the gradation" is almost axiomatic, and it must be
recollected that only a certain amount of opacity will print if the
deepest shadows only are to be kept of the greatest black obtainable
in a print. It is evident that the greater the range of light and
shade that is obtained of a printable density, the more true to
nature the picture will be. For this reason a quick plate with a
moderate gradation is to be preferred--as being most generally
useful--but it should be a plate which is absolutely free from fog,
and it should also be of as fine a grain as possible, the size of
which has something to do with development. This is still more true
when a camera stand and hand exposures are made. With a slow plate
with feebler intensities of light, which must be the case when the
lens is stopped down to admit of hand exposures, the gradation
becomes more steep than if a fairly bright light be employed. A
quick plate does not suffer in the same way, however small the stop
may be. It has already been stated that isochromatic plates may be
employed with a hand camera. For ice and snow views there is not
much to commend their employment, unless to give a deeper shade to
the sky and to the vast crevasses which so often form part of the
foreground. The darker sky allows faint clouds to be visible in a
print when they otherwise would be absent. Pictorially thus the
isochromatic plate has something to recommend it. Celluloid films
have often been substituted for plates by the writer, and excellent
photographs have been obtained on them when they were fairly rapid.
There is not much to be said in their favour as regards weight, for
in most cameras the support for them weighs nearly as much as the
glass plate. There is also a disadvantage in developing them, for
they are not so easily manipulated as a rigid body. For convenience
in travelling, however, they are to be highly commended. A gross of
cut films do not weigh so much as a dozen plates and occupy much
less space in the baggage. The question of the use of a Kodak camera
with its roller slide, has not been brought forward, not because
excellent results cannot be obtained with it, but simply because the
writer prefers to use plates and films which can be got at any time
for the purpose of development.
For travelling on the continent, and to one's mountain destination,
experience has shown that a small hamper is the safest receptacle of
all the necessary kit. A hamper which will contain two camera cases
side by side is really sufficient; but it should be a little greater
in depth. It may be thought that two cameras are to be taken, but
such is not the intention. If a zinc trough be made of the size of
one camera case it will contain all the developing apparatus
necessary, the lantern, and the plates or films, and all the few
etceteras which go to make one happy. (A screwdriver, a file, and
some extra screws, and gummed paper and white blotting paper cut to
the size of the plates should be enough for the etceteras). The
hamper may be arranged so that the camera and view finder may be
taken out without any derangement of the rest of the articles in it.
The developing bottles and cups, with the dishes, may be similarly
extracted. This prevents undue trouble in unpacking and packing. One
grand thing to remember is, pack well but not distressingly tightly,
in other words don't employ an expert packer if you wish for comfort.
Have the hamper a size too large rather than a size too small. Also
be it remembered that it is useless to stopper the bottles with all
sorts of devices at home, and have to pack in an ordinary manner when
once the contents of the hamper have been brought into use. Have your
bottles covered with an indiarubber cap which can easily be removed
and replaced; of course we are assuming that development is to take
place during one's travels, and not to be left over for home.
Personally we think that a speedy development after a view is taken
will give the best picture. It may often happen that an undeveloped
sensitive plate or film will suffer by its travels. There will or may
be scratches and what not, which would be absent if the negative is
finished at the time. The outfit for development which need only be
taken is as follows: four developing dishes, bottles or cartridges of
the dry developer, ammonia diluted to half its strength in a glass
stoppered bottle (if in a wooden case, as for medicine bottles, it
will be a further protection), a couple of tins of hyposulphite
_pounded up_ before the journey, carried in small tins (such tins as
the half-plate platinum paper comes in are very convenient), two or
three empty six ounce medicine bottles with good corks, a two or
four ounce measure, a washing rack with a trough (there is a
folding rack in the market which answers admirably; it has =v= shaped
grooves which never damage the edges of the film, and one rack will
take twenty-two glasses back to back). A zinc trough can be made to
cover the plates with water when in the rack, a lantern (by
preference a paper folding one), a dusting brush, a couple of
dusters, and blotting paper cut into squares the size of the plates,
with which to pack them--it is useful also to have spare pieces of
blotting paper to place beneath the plates when drying, also a piece
of mackintosh to place on the wash stand during developing
operations--an empty pint wine bottle will be got at any hotel and in
this the hyposulphite can be dissolved. The list looks formidable but
the whole can be readily packed in the hamper of the size given. It
will be seen that no intensifying solutions are enumerated amongst
the requisites. A negative is better strengthened in the quiet of
one's dark-room at home.
[Illustration: HOMEWARDS. KARL GREGER.]
Now we must give a hint or two as to the exposures required. We will
suppose that on the plates to be used a satisfactory negative of an
open English landscape, on a bright June day with fleecy clouds in
the sky, can be secured with an aperture of _f_/11 in 1/25th of a
second. If that be so, then on an equally fine day in July or
August, at an altitude of about 6000 feet, the same kind of view
should theoretically be secured in 1/50th second, and a stop of
_f_/16--that is, the photographic light is about four times as
strong. It must, however, be recollected that at this altitude, and
particularly near mid-day, the shadows are not illuminated to the
same degree from the sky. The darker blue sky shows that the light
which at a low altitude goes to make a pale blue sky is to be found
in the direct rays of the sun, and not scattered to give a luminous
sky. As the shadows are principally illuminated by the light from
the sky, it follows that the shadows will be darker at a high than
at a low altitude, for this reason amongst others, the exposure
should not be curtailed to the amount given above. If the aperture
be reduced to _f_/16 it is probable that the exposure of 1/25th
second will be not more than sufficient to give. For our own part we
prefer to give longer and to expose well for the deep shadows,
trusting to development to give us properly "gradated" pictures. As
the sun goes down toward the horizon, the shadows get more illumined
from local reflection, and it is scarcely necessary to alter the
exposure until considerably nearer sunset than at home, when the
exposure must be considerably prolonged. For views in which there is
little but ice and snow, the exposure should be very much curtailed.
There is so little contrast that if the exposure be at all prolonged
the picture will be inevitably flat. The shadows are illumined by an
immense quantity of light reflected from the white surface, and the
difficulty is to get sufficient contrast. The writer well remembers
one set of beautiful views, taken from the top of a mountain some
10,000 feet high, where the eye could see nothing but snow-fields
and ice and swirling masses of clouds. The day was not bright, but
to get a satisfactory picture a stop of _f_/32 was necessary with
only an exposure of 1/70th of a second. Plates given an exposure of
1/25th second with a stop _f_/16 showed little besides a plain white
mass. It would be difficult to give hints for every kind of view.
The judgment of the operator must be brought into play and no
actinometer will be of much use under the varied conditions which
are the rule, not the exception.
Now as to development. The "one-solution" given by the metol and
amidol cartridges are the most readily prepared, and in five times
out of six will scarcely be bettered, but for the sixth time may
fail, because of their "rigidity." For these exceptional negatives,
solutions of an oxidizing agent such as pyrogallol, of a restrainer
(bromide), and of an accelerator are to be recommended. For the
latter, the carbonate (not the bicarbonate) of potash is much to be
recommended, though some prefer ammonia. Two formulæ are given,
either of which will be found extremely useful. When the exposure
has been prolonged enough for details in deep shadows to be brought
out, it will generally happen that over-exposure has been given to
the high-lights, and it is to keep these in the printing state that
care is required. In the old collodion dry plate days, it was very
usual to bring out a complete phantom image of a subject before any
density was given to it. When this was properly out, the intensifier
of silver nitrate and pyrogallol was applied, and the picture
gradually brought up to printing density. It was usually full of
detail in the high-lights and shadows, all of which would be found
in the finished print. Such is the same procedure which we
recommend, strive to get out an image of feeble density but full of
detail, and then give the density.
The plate should first of all be thoroughly soaked in a solution of
the alkali which can be used, and then a few drops of the pyrogallol
solution be dropped into the developing cup with an equal number of
drops of the restrainer. The alkaline solution is then returned to
the cup and again poured into the dish and over the plate. By
degrees the required phantom image will make its appearance, and now
bromide and pyrogallol are added until it is evidently complete. The
plate is then washed in water, a final wash being given in a very
weak solution of acetic acid or citric and water. After a final
rinse with water the plate is treated with the pyrogallol solution
and restrainer in the proportion recommended for the ordinary
development of the plate, omitting the alkali. The density will
begin to appear, and when it flags, a little alkali is added (a few
drops at a time) to the solution. Keep the image fairly feeble at
above half the proper printing density, and fix. The plate should
then be kept for intensification, preferably by Mr. Chapman Jones's,
when a mercury solution is applied, and then a ferrous oxalate to
reduce the latter to the metallic state. It will be found if this
procedure is adopted, that the negative is built up with a greater
range of light gradation than by bringing it out by a one-solution
method of development. If one wishes to exercise artistic treatment,
then in the preliminary stage more importance can be given to any
desired part by applying a camel's hair brush soaked in normal
pyrogallol solution with its restrainer. The prominence thus gained
will be kept in the subsequent operations. When applying the brush
care must be taken that the image blends as it were with the rest of
the picture. No abrupt increase of density must be permitted, as if
it be, the result will be anything but satisfactory.
The following is an ammonia-pyro developer, with which the writer
usually works.
A
Ammonia 1 part.
Water 9 parts.
(Of course, should the ammonia be taken half strength allowance must
be made for the dilution.)
B
Potassium bromide 20 grains.
Water 1 ounce.
(When travelling it is very convenient to have the bromide weighed
out into 20 grain packets.)
P
Pyrogallol dry.
S
Saturated solution of sulphite of soda.
When the view has strong contrasts and the plate has been exposed
for the shadows take of A 30 minims and 2 ounces of water and soak
the plate in it as given above. Then add to the cup, of B 2 drams,
of S 1 dram, and about quarter grain of P. Pour back the solution of
ammonia from the dish, and then apply the mixture till all detail
appears, and proceed as indicated above. A saturated solution of
potassium carbonate may be substituted for the ammonia solution.
Before closing this chapter it may be of use to the reader to
tabulate the number of thicknesses of atmospheres through which
light has to travel at different altitudes of the sun at sea level.
Altitude. Atmosphere.
90° 1.000
80° 1.015
70° 1.064
60° 1.155
50° 1.305
40° 1.555
30° 1.995
20° 2.904
15° 3.809
10° 5.571
5° 10.216
4° 12.151
2° 18.882
0° 35.503
If sunlight outside the atmosphere be represented by 1 and say
1/10th be cut off by 1 atmosphere, then after transmission through 2
atmospheres only .81 will reach the spectator, and if through 3 only
.729. For any atmosphere the diminution will be 1/10th, that is, it
will be .9^_x_ where _x_ is the number of atmospheres.
If we ascend the factor varies, there are less thicknesses of
atmosphere to go through and we get the following table.
Photographically
Visual Transmission Actinic Light
Barometer (Sunlight outside Transmitted
in Inches. the Atmospheric (Sunlight outside
being 1). the Atmospheric
being 1).
30 .853 .639
29 .866 .654
28 .875 .672
27 .884 .689
26 .891 .708
25 .899 .730
24 .908 .746
23 .915 .763
22 .922 .787
21 .928 .800
20 .934 .819
19 .940 .833
This table and the preceding one will enable a calculation to be
made as to the exposure to be given. Thus at sea level with a
photographic brightness of sun of 639,000 candles when nearly
overhead, it will at 5° above the horizon only have a photographic
brightness of about 1000. At about 9000 feet high the photographic
brightness would when the sun is overhead be about 800,000 candles,
and at 5° it would have a value of 350,000, showing the greater
penetration through the thinner atmosphere.
_W. de W. Abney, C.B., F.R.S., etc., etc._
Negative Making.
DEVELOPMENT, INTENSIFICATION, REDUCING, Etc.
[Illustration]
When a sensitive plate has been properly exposed under ordinary
conditions, there is no visible change. The action of light produces
what is known as a _latent image_ or _developable image_, and in
order to convert this into a visible image with sufficient opacity
to be useful for printing purposes, it must be _developed_. In the
operation of development, the plate is treated with some solution
that will act on the exposed parts of the sensitive film and reduce
the silver salts contained therein to metallic silver, in quantity
proportional to the amount of light-action, whilst at the same time
it produces no appreciable change in those parts of the film on
which light has acted the least or not at all, and which correspond
to the darkest shadows of the object that has been photographed. The
solution used for this purpose is called the _developer_.
DEVELOPERS--GENERAL.
The substances that can be employed as photographic developers are
now somewhat numerous, but the most useful for negative making are
pyrogallic acid (also known as pyrogallol, or for brevity as pyro.),
ortol, metol, and hydroquinone (also known as quinol). Ferrous
oxalate is likewise used in special circumstances, but not for
general work. An ordinary developer as mixed for use contains:--
1.--One of the above-mentioned substances (pyrogallic acid,
ortol, metol, quinol) which is the actual developing
constituent, and is known as _the reducer_, but requires the
addition of the next constituent before it can work.
2.--An alkali, which may be sodium carbonate, potassium
carbonate, caustic soda, caustic potash, or, if pyrogallic
acid is used, ammonia. The alkali sets the reducer in action
and is called _the accelerator_.
3.--A soluble bromide, which must be potassium bromide
except when ammonia is used as the alkali, and then it may
be ammonium bromide. The chief use of the bromide is to
retard the action of the developer, and in particular to
prevent its affecting those parts of the film that have not
been acted on by light. For this reason the bromide is
called _the restrainer_ or, sometimes, _the retarder_.
4.--A sulphite, the function of which is to prevent the
solution from becoming strongly discoloured and consequently
staining the film. It also affects the colour of the reduced
silver that forms the developed image, this colour being
browner, and consequently of higher printing opacity, the
lower the proportion of sulphite present. Sodium sulphite
and potassium metabisulphite are the most commonly used.
The composition of a developer has to be so arranged that, whilst
reasonably rapid in its action, it is not so rapid as to be beyond
control, and does not produce "general fog" by acting on those parts
of the film that have not been acted on by light.
[Illustration: AMONG THE ALPS. CAPT. W. DE W. ABNEY, C.B., F.R.S.
ETC.]
DEVELOPMENT--GENERAL OPERATIONS AND PHENOMENA.
A developer is usually compounded immediately before use by mixing
two or more solutions, and in order to ensure uniform action it is
essential that the constituents should be thoroughly mixed before
the liquid is applied to the plate. If the measuring or mixing
vessel is large enough, this can be done by agitating the liquid; if
not, the liquid may be poured once or twice from one vessel to
another.
The quantity of developer necessary for a plate of a given size
depends in some degree upon the size and character of the dish that
is used, and is smallest when the bottom of the dish is quite flat
and has no ridges or grooves. It is false economy to use too small a
quantity, and it may be taken that for a quarter plate 1-1/2 oz.,
for a half plate 2-1/2 or 3 oz., and for a whole plate 4 oz. of
developer should be used.
Ebonite, xylonite, or papier maché dishes are the best for all
operations connected with negative making, since they are not so
liable as porcelain or earthenware to break a plate if it is allowed
to drop into them.
When applying the developer to the plate it is important to cover
the whole surface of the plate rapidly and in such a manner as to
avoid the formation of air bubbles, and the best way is to begin to
pour on the developer at one corner of the developing dish and
whilst pouring somewhat quickly move the vessel rapidly but steadily
along the edge of the dish to the other corner. If there should be
any froth or air bubbles on the surface of the developer, the last
portions should not be poured out of the vessel into the dish, and
then the risk of air bubbles forming on the surface of the plate
will be lessened.
Sometimes after the developer has been poured on and the plate seems
to be uniformly wetted, the liquid will recede from one corner or
one edge of the plate and the part thus left uncovered will appear
as a patch of lower opacity when the negative is finished. This
happens either because the dish is not standing level on the table
or because the bottom of the dish is not flat; sometimes it happens
because too small a quantity of developer has been used.
After the plate has been covered by the developer the dish should be
carefully rocked from time to time, and, for reasons that will be
explained presently, the time required for the first appearance of
the image and the manner in which the different parts of the image
follow one another, should be carefully observed.
If the plate has been correctly exposed, the brightest parts of the
image will appear (as black, of course,) in about a minute, more or
less, according to the temperature, composition of the developer,
and character of the plate, and the other parts will follow steadily
in the order of their brightness, after which the image as a whole
will continue to gain vigour or opacity up to a certain limit. The
essential point is that the principal details in the deepest shadows
of the subject shall appear and acquire a distinct printable
opacity, before the highest lights become so opaque that the details
in them are no longer distinguishable. Whether this condition is
realisable or not depends very largely on the exposure that the
plate has received.
If the image appears in considerably less than a minute and the
different parts follow one another very quickly, the plate has been
_over-exposed_, and the degree of over-exposure is indicated by the
rapidity with which the image appears. In this connection it ought,
however, to be stated that with metol and certain other developers,
even when the plate has been correctly exposed, the different parts
of the image appear almost simultaneously, though the first
appearance may not begin until about a minute after the developer
has been applied to the plate. It follows that with these developers
it is difficult to recognise over-exposure, but it so happens that
they are not suitable developers to use when there is any
probability that the plates have been over-exposed. On the other
hand, if the image is slow in appearing and the brightest parts of
the subject are not followed in due course by the middle tones, the
plate has been _under-exposed_, and there is considerable danger
that the high-lights may become quite opaque before any details have
appeared in the shadows, or even, in extreme cases, in the lower
middle tones, that is to say, in those parts that are next in
darkness to the shadows.
When it is desired, as it frequently is, to alter the composition of
the developer during development, the substance or substances to be
added should be put into the measuring or mixing glass, the
developer poured out of the dish into the glass, and the well-mixed
liquid poured over the plate as before. Any attempt to add
substances to the developer whilst it is in contact with the plate
will probably result in uneven action.
It should be borne in mind that temperature has an important
influence on development, the time required for the first appearance
of the image and for the completion of development being, as a rule,
less the higher the temperature. Further, if the developing
solutions are very cold, it is often almost impossible to obtain
sufficient opacity.
Perhaps the most difficult thing in connection with development is
to know when to stop the process, that is to say, when the image has
acquired sufficient opacity, or "density," as it is often called.
After all the required detail has become visible, the plate from
time to time is lifted carefully out of the developer, allowed to
drain for a moment or two, and then held between the developing lamp
and the eye; the opacity of the image, especially in the highest
lights and deepest shadows, being carefully scrutinised. The
appearance of the image as seen when looking at the back of the
plate, is also carefully observed.
For this purpose it is very much better that the light of the
developing lamp should pass through transparent glass (ruby or deep
orange) so that the flame itself is distinctly visible, instead of
through ground glass or a coloured translucent fabric. Further, the
flame of the lamp, whether gas or oil, should always be turned up to
the same height, for it is clear that if the brightness of the flame
used for making the examination is not fairly constant, all sorts of
variable results will be obtained. For this reason it is much better
to judge the opacity of negatives by artificial light than by
daylight, the intensity of the latter being so variable. A paraffin
lamp with a circular wick and a deep ruby chimney with a metal cap
at the top, answers admirably.
No general rules can be laid down; the appearance of the properly
developed image depends on the thickness of the film, the
granularity of the silver salt, the presence or absence of silver
iodide, and the composition of the emulsion used. Experience only is
of value, and the best way to secure uniformly satisfactory results,
is to keep as far as possible to one brand of plates. With some
plates, for example, very little of the image should appear at the
back of the plate, with others the greater part of the image must be
distinctly visible there.
Sometimes, especially when using small sizes of plates, it is not
easy to tell whether all the necessary detail in the shadows has
been brought out, and this is an important matter, for if the small
negatives are to be used for making enlarged negatives or prints, or
lantern slides, there should be very little clear glass indeed even
in the deepest shadows of the subject. As a rule it may be said that
when every part of the image is at least gray the maximum possible
amount of detail has been brought out. If the greyness begins to
spread to the margins of the plate where it has been protected by
the rebate of the dark slide, general fog is being produced, and, as
a rule, little will be gained, but much may be lost, by continuing
the development for any considerable time after this is observed.
When development is completed the developer is poured off, the plate
is well rinsed under the tap or in two or three changes of water,
and is then ready for fixing.
DEVELOPMENT WITH PYRO-AMMONIA.
This method of development has the advantage that the constituents
can be kept in concentrated solutions, considerable modifications in
the composition of the developer can be made very readily and the
negatives obtained are of excellent printing quality. On the other
hand it cannot be satisfactorily employed with certain brands of
rapid plates, because with them it has a tendency to produce general
fog, and with some other plates, especially when they are old, it
has a tendency to produce what is known as green fog.
Three solutions are prepared:--
REDUCER.
Pyrogallic acid 1 oz. or 10 parts
Potassium metabisulphite[1] 1 oz. or 10 parts
Water, to make up to 10 oz. or 100 parts
ACCELERATOR.
Ammonia 1 oz. or 10 parts
Water, to make up to 10 oz. or 100 parts
RESTRAINER.
Ammonium bromide 1 oz. or 10 parts
Water, to make up to 10 oz. or 100 parts
[1] The metabisulphite is dissolved in about 8 oz. (80 parts)
of water with the aid of heat, and the pyrogallic acid is
then added. When the liquid has cooled it is made up to 10
oz. (100 parts) by addition of water, the whole being well
mixed by shaking.
For each ounce of developer, take 20 minims of reducer, 20 minims of
restrainer and 40 minims of accelerator, and make up to 1 oz. with
water. With some plates 60 minims of accelerator and 30 minims of
restrainer may be used, but any greater proportion of accelerator
has considerable tendency to produce general fog. On the other hand
the proportion of restrainer can often be increased with advantage
since, unless the amount added is very large, its chief effect is to
prevent general fog; 30 minims of restrainer to 40 minims of
accelerator, or 40 minims of accelerator to 60 minims of restrainer
are proportions that can be recommended. Too low a proportion of
bromide should be carefully avoided.
It is very important to ascertain, by careful trial with each brand
of plates that is to be used, what is the maximum proportion of
ammonia that can safely be added, and what proportion of bromide to
ammonia is necessary in order to prevent general fog. As a rule, the
more rapid the plates the smaller is the quantity of ammonia that
can be used with safety.
By far the best plan is to keep development well under control by
adding only part of the accelerator at the beginning of development
and adding the rest as circumstances require.
For each ounce of developer take 20 minims of pyro solution and make
up to the required bulk with water. In another measure mix for each
ounce of developer 40 minims of bromide solution and 60 minims of
ammonia solution, and regard this as the maximum quantity that can
be added with that bulk of developer. Now to the diluted pyro
solution add about a quarter or one-third of the ammonia and bromide
solution, pour this mixture on the plate and observe what happens.
If the mode of appearance of the image indicates that the plate has
been correctly exposed, about half the remaining ammonia and bromide
mixture may be added to the developer at once, and the action
allowed to continue, with occasional rocking of the dish. If
development proceeds satisfactorily and, in particular, if the chief
details in the shadows begin to appear before the highest lights
have become too opaque, it is not necessary nor advisable to add the
last portion of the ammonia and bromide mixture, since the tendency
to general fog and green fog is reduced when the proportion of
ammonia is kept as low as possible. On the other hand, if the
development flags and the appearance of shadow detail is a little
tardy, the rest of the ammonia and bromide mixture must be added.
If the plate seems to be over-exposed, no more of the ammonia and
bromide mixture should be added for some time, until it is seen
whether the quantity already in the developer will suffice to
complete development. If it seems that the over-exposure has been
considerable, a further quantity of pyro solution (10 to 20 minims
per oz.) and also of bromide solution (10, 20, or 30 minims per oz.)
may be added with advantage. Development is then allowed to continue
and the negative is examined from time to time; if it is seen that
the opacity does not increase, or if sufficient detail in the deep
shadows does not appear, further small quantities of the ammonia and
bromide mixture may be added _cautiously_ until the required result
is obtained, waiting a little while to see the result of each small
addition before adding more.
When the plate behaves as if under-exposed, dilute the developer at
once with half the quantity or an equal quantity of water, according
to the degree of under-exposure indicated, and add the whole of the
ammonia and bromide mixture. These modifications should check the
rate at which the high-lights of the subject gain opacity, whilst
accelerating the appearance of the middle tones and shadows. Should
this effect not be produced, further quantities of ammonia and
bromide mixture may be added or, in extreme cases, ammonia alone,
and the developer may be still more diluted with water.
If any considerable parts of the image still show no detail, local
development with a brush may be tried as a last resource. A soft
camel's hair brush, preferably mounted in quill, is used. Some of
the ammonia and bromide mixture is placed in a vessel and diluted
with two or three times its volume of water. One corner or edge of
the plate is raised so that the part to be treated is lifted out of
the developer, the diluted ammonia and bromide mixture is applied
rapidly with the brush, and the plate is allowed to drop gently back
into the developer. The treatment may be repeated if necessary.
Should all these devices fail, the plate is hopelessly
under-exposed.
Sometimes, when working with a diluted developer as just described,
it happens that although all the necessary detail has been brought
out, the image gains in opacity very slowly. Provided that all the
required detail is visible, small quantities of pyro solution may be
added in order to gain opacity more quickly.
[Illustration: TEASELS By Carine Cadby.]
PYRO-SODA DEVELOPMENT.
When sodium carbonate is used as the alkali in place of ammonia the
developer acts somewhat more slowly and is less liable to produce
fog, especially with very rapid plates, and there is very little
tendency to produce green fog. On the other hand, variations are not
so easily made in the composition of the developer. Some people find
the absence of the smell of ammonia a decided advantage.
STOCK PYRO SOLUTION.
The same as for Pyro-Ammonia.
DILUTE PYRO SOLUTION.[2]
Stock pyro-solution 1 oz. or 10 parts
Water 10 oz. or 100 parts
SODA SOLUTION.
Sodium carbonate, crystallised. 1 oz. or 10 parts
Sodium Sulphite 1 oz. or 10 parts
Potassium bromide 10 grains or 0.23 part
Water to make up to[3] 10 oz. or 100 parts
[2] No more of the dilute pyro solution should be made up
than is likely to be used during the same day, but it will
keep well enough for a day or two.
[3] The sodium sulphite and carbonate are dissolved, with the
aid of heat, in about 8 oz. (80 parts) of water, the bromide
added, and the liquid when cold made up to 10 oz. by adding
water.
For use mix equal parts of dilute pyro solution and soda solution
and pour over the plate.
If the exposure has been correct the image will begin to appear in
about a minute, and development is then allowed to go on with
occasional rocking of the dish, until the negative is sufficiently
opaque.
If the plate behaves as if it were under-exposed, _at once_ dilute
the developer with an equal bulk of water and pour it back over the
plate. If the high-lights continue to increase in opacity, but the
rest of the image does not appear, add some more of the soda
solution with or without some more water. Should parts of the plate
still remain blank, apply some of the soda solution to them with the
aid of a brush as described under pyro-ammonia (page 32).
If the rapid appearance of the image indicates that the plate is
over-exposed, at once pour off the developer into a measure or
mixing glass and rinse the plate well with water. Add to the
developer a small quantity of potassium bromide solution (1 in 10 of
water) which should be kept at hand for this purpose. A small
quantity of pyro stock solution may also be added. The developer is
then poured over the plate again. When the over-exposure seems to
have been considerable, the amount of potassium bromide added may
amount to 4 grains (or 40 minims of the 1 in 10 solution) per ounce
of the developer, but this proportion should not be exceeded; even
small quantities of bromide in the pyro-soda developer have a marked
influence in retarding development.
When there is reason to suspect over-exposure, not more than half
the soda solution should be added at the beginning of development,
and the rest may be added or not, as the case may require.
DEVELOPMENT WITH ORTOL.
ORTOL SOLUTION.
Ortol 130 grains or 1.5 parts
Potassium metabisulphite[4] 65 grains or 0.75 part
Water to make up to 20 ounces or 100 parts
SODA SOLUTION.
The same as for pyro-soda.
[4] See foot-note to page 30.
Mix equal parts of ortol solution and soda solution.
This developer behaves in much the same way as pyro-soda and gives
very similar results. It has the advantage, however, that it does
not stain the fingers, and has practically no tendency to produce
either fog or stain on the plates. Moreover the same quantity of
solution can be used for several plates; when the action becomes
perceptibly slower or weaker, part of the old solution is poured
away and an equal quantity of freshly mixed ortol and soda solutions
is added.
The chief differences to be observed are (1) that the different
parts of the image follow one another more rapidly than with
pyro-soda, even though the plate may have been correctly exposed,
and (2) the colour of the reduced silver is somewhat bluer than with
pyro-soda, and therefore in order to obtain the same degree of
_printing_ opacity, as distinct from visual opacity, development
must be carried a little further.
Apart from these differences, what has been said of pyro-soda holds
good for ortol soda and need not be repeated.
DEVELOPMENT WITH HYDROQUINONE (QUINOL).
QUINOL SOLUTION.
Hydroquinone 90 grains or 2 parts
Sodium sulphite 1 oz. or 10 parts
Water to make up to 10 oz. or 100 parts
ALKALI SOLUTION.
Potassium carbonate (dry) 1 oz. or 10 parts
Potassium bromide 20 grains or 0.46 parts
Water to make up to 10 oz. or 100 parts
Mix two parts of hydroquinone solution with one part of alkali
solution and one part of water, or, if a more energetic developer is
wanted, mix equal volumes of the hydroquinone and alkali solutions.
Hydroquinone is not an advantageous developer for general purposes,
but it is useful when negatives are required showing strong contrast
between the highest lights and the deepest shadows, and especially
when it is important that there should be no deposit at all in the
deepest shadows. This is the case, for example, when copying line
engravings, pen and ink drawings and similar subjects.
DEVELOPMENT WITH FERROUS OXALATE.
This method of development also is not well adapted for general
work, but it is invaluable for certain purposes. The reduced silver
has a pure grey-black colour and there is exceedingly little
tendency to produce fog of any kind. On the other hand, the
developer admits of little modification in its composition and
therefore the exposure must be fairly correct. It is also important
to avoid contamination with even minute quantities of hypo, since
this substance very readily causes stains.
FERROUS SULPHATE SOLUTION.
Ferrous sulphate 2-1/2 oz. or 25 parts
Sulphuric acid Small quantity
Water to make up to 10 oz. or 100 parts
About three-quarters of the total quantity of water is mixed with a
small quantity (not more than 50 minims per 10 ozs., or one part per
100) of sulphuric acid, and the ferrous sulphate (proto-sulphate of
iron) which must be in clear pale green crystals without any
yellowish incrustation, is dissolved in it with the aid of a gentle
heat. After the solution has cooled, it is made up to the specified
volume with water. This solution alters when exposed to air, and
should, therefore, be kept in small (2 oz.) bottles, filled up to
the neck and tightly corked.
OXALATE SOLUTION.
Potassium oxalate 10 oz. or 25 parts
Potassium bromide 40 grains or 0.23 part
Water to make up to 40 oz. or 100 parts
For use take four parts of oxalate solution and one part of ferrous
sulphate solution, pouring the latter into the former and _not vice
versa_. In order to obtain slower action with a rather softer image
and a slightly browner deposit, the developer may be diluted with an
equal volume of water. Slower action, with slightly increased
printing contrasts, and clearer shadows, results from an increase in
the proportion of bromide.
FIXING.
After development is finished, the dark-coloured reduced silver that
forms the image remains mixed with a considerable quantity of
semi-opaque, yellowish unaltered silver bromide, which would not
only interfere with the printing, but would also gradually darken
when exposed to light. The negative must therefore be "fixed" by
dissolving out the unaltered silver bromide, and this is
accomplished by immersing the plate in a fairly strong solution of
sodium thiosulphate (formerly called sodium hyposulphite) commonly
known as "hypo." The usual strength of the fixing is as follows:
FIXING BATH.
Hypo (sodium thiosulphate) 10 oz. or 25 parts
Water to make up to 40 oz. or 100 parts
A solution of double this strength is, however, not unfrequently
used, and acts more rapidly, especially in cold weather.
The developed plate, after being well rinsed with water, is placed
in the fixing bath and allowed to remain in it with frequent rocking
until the silver bromide has all been dissolved out of the film.
This is ascertained by lifting the plate out of the dish and looking
at the back by reflected light, the plate being held in front of
something dark. It is not difficult to see whether the silver
bromide has all disappeared or not, but in order to ensure complete
fixing the plate must not be taken out of the bath as soon as this
has happened, but should be left in for a few minutes longer, the
dish being rocked so that the dissolved silver salt may diffuse out
of the film into the fixing bath.
When removed from the fixing bath the plate should be allowed to
drain into the bath for a few moments and should then be washed for
five or ten minutes in running water under the tap. It is best to
put the plate in a dish standing on the sink and have a piece of
flexible indiarubber tubing reaching from the tap to within a couple
of inches or so of the top of the dish, so that the water may not
splash too much. After washing in this way, the plate is placed in
a grooved zinc rack, which is immersed in a tank (preferably of
zinc), containing sufficient water to completely cover the plates,
and here it remains until the whole batch of plates in hand has been
developed and they can all receive their final washing together. The
plates stand upright in the rack, and the entrance and exit of the
water must be so arranged that the water enters at the bottom and
overflows at the top, or, what is perhaps better, enters at the top
and is drawn off from the bottom, the waste pipe opening at the
bottom of the tank and being bent and carried upwards until its
mouth is at the level at which the water is to stand in the tank.
When running water is not available the plates may be washed in
dishes. After being well rinsed to remove the adhering hypo
solution, the plate is covered with water (about 3-1/2 oz. for a
half plate or 5 oz. for a whole plate) and allowed to remain with
frequent rocking for five or six minutes. The water is then well
drained off, a second quantity added and allowed to remain for the
same time as before, with frequent rocking, when it is poured off in
its turn. Treatment in this way with six successive quantities of
water will remove all the hypo, provided that the film has not been
treated with alum.
Another plan, rather less troublesome, but also less expeditious, is
to place the rack containing the plates in a tank not much more than
big enough to hold it, taking care that there is not less than two
inches between the lower edges of the plates and the bottom of the
tank. After standing for some time the rack and the plates are
slowly and carefully lifted out and allowed to drain, the tank
emptied and filled with fresh water, and the rack and plates then
replaced. Eight or ten successive quantities of water applied in
this way should remove all the hypo, but if there is any doubt on
this point the plates, after they are supposed to be washed and have
been removed from the tank, should be allowed to drain into a
measuring glass or into a dish, the contents of which are afterwards
transferred to a measuring glass and mixed with a small quantity of
a solution of silver nitrate. If the plates are really completely
washed nothing will happen, or at most a white precipitate will be
produced which _will remain white_ if not exposed to daylight. If,
on the other hand, the plates still retain hypo, the silver nitrate
will produce a precipitate which will gradually become orange and
eventually dark brown. Should this happen, the washing must be
continued.
[Illustration]
DRYING.--If the negatives are allowed to dry in the rack in which
they were washed, the process is slow, and sometimes if the washing
has not been complete, the middle portions of the negatives, which
dry last, are less opaque than the rest. An excellent method of
drying negatives rapidly and in such a way that no dust can fall on
the film, is to drive nails (preferably of copper) into a wall or a
board fixed against the wall, at distances apart depending on the
size of the plates. Each plate then rests, with the film
downwards, between a pair of nails, the lower corner of the plate
resting against the wall, as shown on previous page.
[Illustration: WINTER TIME ON THE ALPS. CAPT. W. DE W. ABNEY, C.B.,
F.R.S., ETC.]
ALUM BATH.--It is frequently recommended that all plates should be
immersed in a strong solution of alum, for the purpose of preventing
"frilling" by hardening the film. Its use is, however, attended with
the great disadvantage that liquids diffuse into and out of a film
so treated with much greater difficulty than in the case of an
ordinary film, and consequently if the film is alumed between
development and fixing, the fixing is not only much slower, but the
washing after fixing requires a very much longer time. If,
therefore, the alum bath is used at all, it should not be applied
until after the film has been well washed after fixing. The
following solution may be used:--
ALUM BATH.
Alum 1 oz. or 5 parts
Water 20 oz. or 100 parts
If a strong solution of alum is applied to the plate for a long
time, the film may become so thoroughly hardened that it partially
loses its adhesiveness, and there is a possibility that it will
begin to peel from the glass after the negatives have been stored
for some time in a dry place. The solution given above is quite
strong enough and plates need not be immersed in it for more than
five minutes, after which they must, of course, be again well
washed. The hardening of the film, if not carried too far, no doubt
makes it less liable to be injured by abrasion and the like.
FRILLING.--It sometimes happens that during the various operations
of development, fixing and washing, the film begins to leave the
plate and rise in puckers along the edges. This is known as
"frilling," and in bad cases it may spread until a large part of the
film has detached itself from the glass. It is due to excessive or
irregular absorption of water by the gelatine, and at one time was
commonly met with, but it rarely occurs with the dry plates of the
present day. It is most likely to arise if there is any considerable
difference of temperature between the various liquids and the
wash-water, or during very hot weather when all the liquids are much
warmer than usual.
When frilling does occur, the plate must be treated carefully, so as
to avoid tearing the film, but unless it is very bad and shows a
tendency to spread, all the operations, including washing after
fixing, should be completed before any special measures are taken to
remedy the defect. On the other hand, if the frilling spreads
rapidly, the plate should be carefully rinsed two or three times
with water and placed for five minutes in the alum bath, with
occasional gentle rocking, after which it is again well washed to
remove the alum, and the various operations are completed. There is
one exception to the procedure just indicated; if the frilling
becomes bad while the plate is being fixed or during washing after
fixing, the alum must not be applied until the fixing and the
washing after fixing are completed. If something must be done in
these circumstances, the plate, after draining, but without any
previous washing, may be placed for about ten minutes in a saturated
solution of common salt. It can afterwards be put back into the
fixing bath, also without any intermediate washing, and the
remainder of the process carried through.
Although the methods just described will check the frilling, they
will not remove its effects. For this purpose the plate after its
final washing is allowed to drain thoroughly and is then immersed in
methylated alcohol, preferably of the old kind, though the new kind
can be made to do. The alcohol abstracts water from the film, which
consequently shrinks to its original size and can be pressed back
with the fingers into its proper position on the plate. Should the
film be opalescent it should be removed from the first quantity of
alcohol and placed in a second quantity, after which it should be
set up to dry. The plates should not remain too long in the alcohol
or the gelatine will contract too much.
DEFECTS IN NEGATIVES.
A perfect negative presupposes a perfect plate, correct exposure,
and correct development stopped at exactly the right time. It is
almost unnecessary to say that all these conditions are rarely
satisfied, and consequently most negatives fall more or less short
of perfection. The defects may be broadly grouped under two heads,
namely, those due to imperfections existing in the film before
exposure, and those due to defects or errors in the way in which the
plate has been treated. It will be more convenient to deal with the
latter, and larger, group first, but there is really no hard and
fast division between them.
THE NEGATIVE IS THIN, or in other words, whilst showing good
gradation, and sufficient relative contrast between the different
parts, is as a whole lacking in opacity or printing strength, and
gives prints that are deficient in vigour and contrasts. The plate
has been removed from the developer too soon, and the remedy is to
intensify the image (see p. 51). Sometimes the want of opacity is
due to the fact that the developer was too cold.
THE NEGATIVE IS TOO DENSE OR OPAQUE and consequently although
showing good contrasts and gradations, takes a long time to print,
especially on dull days. The developer has been too energetic, or
development has been continued too long; the remedy is to reduce the
image (see p. 50).
THE IMAGE IS "FLAT," or shows comparatively little contrast between
the highest lights and the deepest shadows. This may, of course, be
due to the absence of contrasts in the subject photographed; it is
commonly due to over-exposure; it may be caused by using a developer
containing too little reducer, or restrainer, or both, and too much
alkali; sometimes it arises from a defect in the quality of the
emulsion, or from the fact that the plate has been coated with an
abnormally thin film of emulsion.
THE IMAGE IS "HARD," or shows excessive contrasts between lights and
shadows, and is defective in the range of its half-tones. This is
probably due to under-exposure, but may have been aggravated by the
use of a developer containing too much bromide or too little alkali.
Local reduction (see p. 50) may partially remedy the defect.
FOG.--A more or less marked grey deposit of reduced silver extends
over the whole surface of the image. It may be due to over-exposure,
in which case the edges of the plate that have been protected by the
rebate of the dark slide usually remain clear. It may also be caused
by using a developer containing too much alkali, or too little
restrainer, or both, or by the plate having been exposed to actinic
light outside the camera, including the light from the dark-room
lamp if the glass or coloured fabric used as the screening material
is not efficient. In any of these cases the defect would be
observable up to the extreme edges of the film.
The character of the dark-room light should be tested by exposing
one half of a plate to it at a distance of say nine or twelve inches
for five or ten minutes, the other half of the plate being
protected by some opaque substance. The best plan is to put the
plate into a dark slide and draw out the shutter half-way. After
exposure the plate is treated with a developer in the usual manner,
and it can then be seen whether or no the light has exerted any
action on the plate.
Slight general fog may as a rule be neglected, but if the amount of
fog is at all considerable the plate should be treated with a
reducer, and afterwards the image can, if necessary, be intensified.
GREEN FOG.--The surface of the film shows a peculiar brilliant green
or yellowish-green lustrous appearance, generally in patches, when
examined by reflected light, but is more or less distinctly pink
when the plate is looked through. This effect is rarely observed
except when pyro-ammonia has been used as the developer, and it most
frequently occurs with old plates, especially if development has
been long continued or has been forced by the addition of
comparatively large quantities of ammonia.
If the green fog is only slight it does not affect the prints made
from the negative, but in bad cases the prints have a patchy
appearance and are less deeply printed at those points where the
green fog is worst. Two methods are available for the removal of
green fog.
In one of these the plate, after being fixed and washed, is placed
in a hypo solution of half the strength of the ordinary fixing bath,
and to this hypo solution is added a very small quantity of a
solution of potassium ferricyanide, and the mixture is allowed to
act on the plate for some time, the dish being rocked occasionally.
The green fog will gradually disappear and some more of the
ferricyanide may be added, if necessary, to secure this end, but it
is important to keep the proportion of ferricyanide as low as
possible, otherwise the image itself will be reduced. For this
reason, if it is seen or suspected that the green fog is likely to
be bad, development should be carried a little farther than usual in
order to allow for the slight reduction that accompanies the removal
of the green fog.
The other plan is to immerse the plate in a dilute solution of
ferric chloride (perchloride of iron) until the green fog has been
completely bleached, then wash, first in a dilute solution of oxalic
acid and afterwards in water, and finally treat with a developer,
preferably ferrous oxalate. The green fog is converted into a very
fine grey deposit which is almost invisible and has no appreciable
effect on the printing qualities of the negative.
BLACK SPOTS may be due to particles of dirt that have been allowed
to lodge on the film during one or other of the operations, or
during drying. They may also be due to particles in the emulsion,
and in the latter case are generally round and sharply defined.
BLACK MARKS of the nature of irregular streaks, looking, so to
speak, like black scratches, are generally due to mechanical
abrasion of the film. Pressure produces a developable image similar
to that produced by the action of light.
BLACK BANDS, indistinct or nebulous at the edges, are sometimes
caused during the coating of the plate with the emulsion, in which
case they, as a rule, extend all the way along or across the plate.
More commonly they are due to defects in the hinges of the dark
slides, which may produce the bands either by allowing light to pass
through, or by giving off exhalations that affect the plates if they
are allowed to remain in the dark slide for a long time. If the
bands are due to the hinges, they will, of course, correspond with
them in position, and if the hinge is double, in the distance
between them.
TRANSPARENT BANDS, or bands showing less opacity than the rest of
the image, are sometimes caused by exhalations from the material
forming the hinges of the dark slides.
TRANSPARENT SPOTS if small ("pinholes"), are generally due to the
presence of particles of dust on the surface of the plate when it
was exposed. Prevention lies, of course, in carefully dusting the
plate and the dark slide with a soft, clean, dry camel's hair brush,
before putting the former into the latter. If the spots are larger
and circular, they are due either to the formation of air bubbles on
the surface of the plate during development, or to the presence in
the film of insensitive particles.
UNEVEN OPACITY OR DENSITY, varying gradually from one end or side of
the plate to the opposite end or side, is due to uneven coating of
the plate. If there is a distinctly defined patch, less opaque than
the rest, the plate was not properly covered by the developing
solution.
STAINS.--A uniform stain, of a yellowish or brown colour, is
produced when the pyro developer contains too small a proportion of
sulphite or is allowed to act for a very long time. Such a stain is
rarely observed with the other developers mentioned above. The pyro
stain can be more or less completely removed by immersing the plate
for some time, with repeated rocking, in the alum solution given
above, 1 drachm of sulphuric acid being added to every 10 ounces.
The plate must afterwards be well washed in soft water. Similar
stains in patches may be caused by using dirty dishes or a developer
that has become turbid by being frequently used.
DEEP YELLOW-ORANGE OR BROWN STAINS, appearing gradually in patches
or all over the negative, some time after it has been fixed, and
washed, and dried, are due either to imperfect fixing or to
incomplete washing after fixing. There is no practicable remedy.
[Illustration: DOCK By Carine Cadby.]
HALATION.--When the subject photographed includes some part much
more brightly lighted than the rest, such as a window in an interior
subject, the details of the bright part are not only lost, but the
image of it seems to spread in all directions, obliterating the
details of the surrounding portions. The effect is especially
noticeable when the subject includes dark parts which necessitate a
somewhat long exposure. A window at the end of a long dimly lighted
interior, or dark trees against a bright sky are cases in point. The
effect is really due to the fact that the sensitive film is not
perfectly opaque, and some of the incident light passes through the
film and is reflected from the back surface of the glass on to the
under side of the film, producing a blurred image superposed, as it
were, on the normal image formed at the surface of the film by the
action of the direct light. The effect is known as "halation." It is
prevented by having a perfectly opaque film, which is a condition
difficult to realize in practice, and which, moreover, introduces
certain other disadvantages. It is also prevented by coating the
back of the plate with some substance that will absorb the rays that
have passed through the film, and so prevent their being reflected
back against the under side of the film. The substance used must
either be opaque or must have a deep orange, brown, or red colour,
and it must have the same refractive index as the glass, otherwise
the reflection will not be prevented. For practical convenience it
must also be easily applied and easily removed. Many substances have
been recommended but nothing is so good as caramel, prepared by the
action of heat on sugar. In order to get the mixture to dry
completely after it has been applied, a somewhat troublesome process
of purification is necessary, but caramel specially prepared for the
purpose can now be obtained from dealers in photographic materials.
The caramel (which is a solid substance) is dissolved in just enough
water to make a thick syrup, which is carefully applied to the back
of the plates in a thin layer by means of a flat brush.
If the caramel does not dry properly the solution may be thoroughly
mixed with about one quarter (or more) of its weight of very finely
powdered burnt sienna or burnt umber, "ground in water."
After being coated, the plates require some time to dry, and must,
of course, be carefully protected from light. If the dark-room is
thoroughly dark, the plates may be put up to dry in the same manner
as negatives (see page 40), but if the dark-room is not suitable,
some sort of drying box must be used.
After exposure and before development the backing is removed with a
damp sponge; if caramel only is used in a form completely soluble in
water, it need not be removed unless a developer is being used that
is to be applied to several plates in succession.
REDUCTION.
When a negative is too opaque or dense it must be reduced by
dissolving away part of the silver that forms the image. The same
process is also applied for the removal of general fog, sometimes
with a view to subsequent intensification.
The simplest solution to use for this purpose is known as the Howard
Farmer reducer and is a solution of hypo mixed with a small quantity
of potassium ferricyanide (red prussiate of potash).
FERRICYANIDE SOLUTION.
Potassium ferricyanide 1 oz. or 10 parts
Water to make up 10 oz. or 100 parts
This solution must be protected from light if it is to be kept for
any length of time.
The negative which, if it has been previously dried, must be soaked
in water for some time until it is thoroughly and uniformly wetted,
is placed in some fresh hypo solution (the ordinary fixing-bath
solution diluted with an equal volume of water) to which a small
quantity of the ferricyanide solution has been added, and the dish
is rocked repeatedly to ensure uniform action. The rapidity of the
reducing action depends on the proportion of ferricyanide solution
added, and it is very important not to add too much, otherwise the
process gets out of control and reduction goes too far. The image
should be carefully watched and the plate removed from the solution
and rapidly washed before the apparent reduction is quite as great
as it is intended to be. It is much better to stop too soon than too
late, because if it is found that a little further reduction is
necessary, the plate can be again immersed in the hypo and
ferricyanide.
The ferricyanide reducer can be applied locally for reducing
high-lights, halated windows, etc., and this is often very valuable,
especially in the case of under-exposed negatives. A small quantity
of hypo and ferricyanide solution is mixed in a measuring glass or
some other suitable vessel. The plate is immersed in plain hypo
solution in a white dish for a short time and is then raised by one
corner or one edge until the part to be reduced is above the
solution. The mixture of hypo and ferricyanide is carefully applied
with a camel's hair brush to the parts that are too opaque, and
after a few moments the plate is allowed to slip back into the hypo
solution and the dish is rocked. If the reduction is not sufficient,
the same proceeding is gone through as often as necessary. The
reducer should not be allowed to act too long before putting the
plate back into the hypo, otherwise the reduction may spread further
than is desired. Further, the reducer must not be too strong
(_i.e._, contain too much ferricyanide), otherwise it will produce
brownish stains and the action may be too energetic.
The other reducer is known as Belitzski's reducer, and is made up as
follows:--
Ferric potassium oxalate 1 oz. or 5 parts[5]
Sodium sulphite 1 oz. or 4 parts
Oxalic acid 1/4 oz. or 1 part
Hypo solution (25 in 100) 5 oz. or 25 parts
Water 20 oz. or 100 parts
[5] The formula in "parts" does not strictly correspond with
that in ounces, but the difference is immaterial.
The constituents must be dissolved in water in the order given. The
solution can be used at once and it keeps fairly well if protected
from light, in well corked bottles filled up to the neck.
INTENSIFICATION.
Intensification is a process in which the opacity of the image is
increased by adding some fresh matter, metallic or otherwise, to the
reduced silver that constitutes the developed image.
The usual plan is to bleach the image by means of a solution of
mercuric chloride (mercury perchloride or corrosive sublimate),
which converts the dark-coloured silver into a white mixture of
silver chloride and mercurous chloride, and this is subsequently
treated with some re-agent which will reconvert the image into a
dark product of greater opacity than the original.
It is absolutely essential to successful intensification that the
negative be completely fixed and completely washed after fixing, for
any trace of hypo left in the film will give rise to brown stains.
It is also important, in order to prevent stains of another sort and
to secure uniform action, that the mercuric chloride solution be
mixed with a small quantity of hydrochloric acid. Too much acid will
cause frilling. If the negative has been dried it must be immersed
in water for, as a rule, not less than half-an-hour, in order that
it may be thoroughly and uniformly wetted.
MERCURIC CHLORIDE SOLUTION.
Mercuric chloride 1 oz. or 5 parts
Hydrochloric acid 1-1/2 drachms or 1 part
Water to make up to 20 oz. or 100 parts
When uniform intensification is required the negative is allowed to
remain in this solution until it is completely bleached. If,
however, it is desired to intensify the shadows more than the
high-lights, the plate should be removed from the solution as soon
as the shadows have bleached, and should be rapidly washed in order
to stop the action on the more opaque parts of the image.
In either case the negative must be thoroughly washed after
bleaching, and the water used must be soft water. Hard water tends
to produce a precipitate of the mercury salt in the film, which may
subsequently lead to stain or fog.
Perhaps the best plan of all, when constant results are desired, is
to treat the bleached negative with the ferrous oxalate developer,
which will gradually convert the white image into a black one, after
which the plate is thoroughly washed and dried. It is recommended
that the first water used for washing should be slightly acidified
with oxalic acid.
Instead of using ferrous oxalate the bleached plate may be treated
with a weak solution of ortol or metol to which some sodium
carbonate (soda crystals) solution has been added, but _no
sulphite_. After the image has blackened completely the plate is
washed.
With any of these methods if the first intensification is not
sufficient, the plate may be again bleached with the mercury
solution and the process repeated.
An old method, frequently used, is to treat the bleached plate with
dilute ammonia, which converts the white image into a dark brown one
of very considerable printing opacity. The results are often very
good, but are somewhat uncertain, since the precise effect obtained
depends on the strength of the ammonia solution and the time during
which it is allowed to act. With somewhat strong ammonia, allowed to
act for a fairly long time, part of the intensification first
produced is removed. This affects the shadows more strongly than the
lights and the result is to increase the contrast of the negative,
which is very useful for certain purposes.
The negatives intensified with mercury solution followed by ammonia
are more liable to spontaneous change and deterioration than those
intensified with mercury solution followed by one of the developers.
The latter, in fact, if properly washed, may safely be regarded as
permanent.
URANIUM INTENSIFIER.--A very considerable degree of intensification
can be obtained by the use of the uranium intensifier, which is very
different in its mode of action, and is a little uncertain in its
results. A solution containing potassium ferricyanide and a uranium
salt, generally the nitrate, is applied to the negative, and a
deposit of a deep orange-red colour is formed upon the silver image
and very greatly increases its printing opacity. The great
difficulty is to prevent this deposit forming on the whole of the
film, and it is absolutely necessary that every trace of hypo should
be washed out of the film. The addition of acetic acid to the
solution not only promotes uniformity of action, but also helps to
keep the shadows of the image clear.
FERRICYANIDE SOLUTION.
The same as for the ferricyanide reducer.
URANIUM SOLUTION.
Uranium nitrate 1 oz. or 10 parts
Water to make up to 10 oz. or 100 parts
THE INTENSIFIER.
Uranium solution (1:10) 1 drachm or 5 parts
Ferricyanide solution (1:10) 1 drachm or 5 parts
Acetic acid (glacial) 2 drachms or 10 parts
Water to make up to 2-½ oz. or 100 parts
The negative is placed in this solution and allowed to remain with
occasional rocking until the degree of intensification is sufficient,
which can only be learnt by experience. If it is seen that the
deposit is beginning to form on the clear parts of the negative, the
plate should be at once removed. After intensification the plates are
well washed. If the water is "hard" the intensification will be
slightly reduced during washing, and this is often useful in removing
a slight stain over the whole of the plate. Treatment with water
containing a small quantity of ammonia or sodium carbonate removes
the whole of the deposit, but leaves the original image slightly
reduced and also partially altered in composition.
VARNISHING.
A negative after been thoroughly dried may be used for printing
without any further treatment, especially if only a few prints are
required and the ordinary ready sensitized papers or emulsion
papers are used. It is, however, better to protect the negative from
mechanical as well as chemical injury by means of a film of hard
varnish or collodion.
Many excellent negative varnishes can now be purchased, and the
general mode of application is the same. The negative must be
thoroughly dry, and in order to secure this and to make the varnish
flow more easily, the negative is very carefully heated in front of
a fire or over a small stove until it is just warm, but not hot. The
negative is best supported by means of a pneumatic holder held in
the left hand, and a fairly large pool of varnish (the exact amount
can only be learnt by experience) is poured on the plate somewhat
towards the right-hand top corner, and by carefully tilting the
plate it is made to run first to the nearest corner, then along the
edge to the further left-hand corner down to the nearer left-hand
corner, and back to the right-hand bottom corner, from which it is
poured into a bottle. The plate is gently rocked whilst it drains
into the bottle, and as soon as the varnish ceases to drop the plate
is again carefully warmed until the back of it is just too hot for
the back of the hand to bear, after which it is placed in a rack to
cool.
It is necessary that the varnish should be quite clear and free from
any solid particles, and if necessary it must be filtered through a
plug of cotton wool moistened with alcohol and placed in the apex of
a glass funnel which is resting in the neck of a clean and dry
bottle. Since dust may fall into the varnish whilst it is on the
negative, it is the best plan to pour the excess of varnish off the
negative into a second bottle instead of back into the first, out of
which it was poured. To put it in another way, one bottle should be
kept for the clear varnish, and a second bottle for the varnish
poured off the plate. When the second bottle is full, its contents
are filtered into the first bottle for use again.
Instead of varnish, a film of collodion, toughened by the addition
of a few drops of castor oil, and known as "leather" collodion, may
be used. The collodion is applied to the plate in the same way as
varnish except that the plate is not warmed.
_C. H. Bothamley._
[Illustration]
_Lenses._
[Illustration]
Photographs of flat objects such as leaves, lace, drawings, etc.,
can be made by simply putting the object on the sensitive surface
and exposing the arrangement to light. But this method will not
serve if the photograph is wanted of any other size than the
original, nor with solid objects of any size, except perhaps in the
production of full-size profiles of faces. It is therefore quite the
exception in photography to "print" directly from the object itself,
and the only alternative is to produce an image on the sensitive
surface.
All illuminated objects reflect light and so become for practical
purposes sources of light, just as the moon shines, as we say,
although it only shines because it is shone upon by the sun. The
simplest source of light to consider is a point of light, and if we
can get a dot of light on a white surface from a point of light we
have at once an image of that point of light. The smaller the dot
the sharper or more perfect is the image, the larger the dot the
more diffused or fuzzy is the image. It is impossible by any known
means to get the dot so small that it is an actual point, that would
be absolute perfection, and on the other hand there is no size of
the dot at which it can be definitely said that it ceases to be an
image. Every point of an illuminated object is a point of light, and
fine definition consists in keeping these points separate in the
image. So far as the dots overlap they are confused. Confusion, or
diffusion, or fuzziness is sometimes desirable, as for example in a
portrait, which may be excellent although it is impossible to
distinguish in the picture the individual hairs on the person's
head.
[Illustration: Fig. 1.]
The simplest means for getting an image is a small hole in an opaque
screen. In fig. 1, two points of light, A and B, shine through the
hole in the screen S and produce two dots of light, _a_ and _b_, on
the surface T. The two pencils of light do not practically interfere
with each other although they pass through the same small hole, nor
would any greater number; so that an illuminated object, which may
be regarded as consisting of an infinite number of points of light,
would give an image on the surface T. The disadvantages of a small
hole, or "pinhole," for the production of images are (1) it must be
so small that it lets very little light through and therefore gives
a very feeble image, (2) that it can never give a sharp image. The
first disadvantage is obvious. With regard to the second, a little
consideration will show that the image of a point must be larger
than the hole itself, it is always larger though it may have a
central brighter part that is smaller. If the hole is reduced in
size beyond a certain limit, it gives an increased spreading of
light on the surface, so that a sharp image can never be produced.
[Illustration: Fig. 2.]
Now the function of a lens is to obviate these drawbacks as far as
possible; namely, to let more light through and form a brighter
image, and to give sharper definition. In figure 2, the lens L
collects all the light that falls upon it from the point B, and
condenses it to the point _b_ on the surface T. The light from the
point A that falls on the lens is also condensed and would be
brought to a point or "focus" at _a_ beyond the surface T, but on
the surface the light forms a patch of considerable size. Suppose
that the lens is thirty times the diameter of the pinhole its area
is 900 times as large, and the light that falls upon it is 900 times
as much as the light that passes through the hole. Such an enormous
gain of light is worth so much that photographers willingly put up
with the very many imperfections of lenses for the sake of it, and
if to this gain there is added the superior definition that is
possible, it will be seen that lenses are indispensable to the
photographer. To take a Daguerreotype portrait with a pinhole might
have required several days if not weeks exposure of the plate and
therefore would have been impossible, so that the gain in brightness
of image is a great deal more than a mere convenience.
It will be observed in figure 1 that both points of light, A and B
produce images on the surface T, although they are at different
distances from it, but in fig. 2, although the effect of the lens is
to concentrate the light from both points to two other points, one
of these is beyond the surface T. This is a disadvantage inherent in
lenses. They have so many other imperfections or "aberrations" that
it is desirable to consider these separately. The reader should bear
in mind that the one aim of opticians in perfecting lenses is to
concentrate as much light as possible from each point in the object
to a corresponding point, or as small as possible a dot, in the
image, and the image should be flat because the plates used in
photography are flat.
[Illustration: Fig. 3.]
_Spherical Aberration._--The surfaces of lenses are always ground to
spherical curves, and this fact makes it impossible for a single
lens, such as that shown in figure 2, to bring to a point all the
light that falls upon it from a point. If a pencil of light passes
through a piece of glass with sloping sides it is bent or
"refracted" towards the thicker part of the glass, and the greater
the angle of inclination of the two sides the more is it refracted
from its original path. In figure 3 it is clear that the two sides
of the lens shown in section are inclined to each other at a
continually increasing angle as they approach each other at the
edges of the lens. The refracting effect of the lens increases from
the centre outwards, and it increases to a greater extent than is
necessary to bring the incident light to a point. The focus of the
pencils of light that pass through the edges of the lens is nearer
to the lens than the focus of the pencils that pass through its
central part. In the figure two foci are shown, _a_ and _b_, but of
course, in fact, intermediate parts of the lens produce intermediate
foci, and what should be a point in the image, is spread out into a
line on the axis of the lens, and all along this line is surrounded
with the light that either is coming to a focus or that has come to
a focus and has spread out again. On a screen placed at _b_ there
would be a point of light surrounded by a halo, while at _a_, nearer
the lens, the central focus or point is surrounded by a brighter or
more condensed light, and the appearance is of a circular patch of
light with a brighter boundary. This is positive spherical
aberration. Negative spherical aberration is due to over correction,
the focus of the light passing through the margins being furthest
from the lens, and the appearances on a screen are of course
reversed.
_Chromatic Aberration._--When light is refracted, that is bent out
of its original path by a single piece of glass, it is not refracted
as a whole, but each constituent behaves as if none other were
present. Ordinary white light or daylight is a mixture of many
coloured lights as seen in the rainbow, and when refracted, the blue
is bent more than the green, the green more than the yellow, and the
yellow more than the red. So that using a single lens the focus of
the blue light is nearer the lens than the focus of the red light
and the others come in between. In figure 4 this is represented in
an exaggerated degree to make it more distinct. It will be observed
that a screen placed at the focus of the blue light will show a
reddish margin and if removed further from the lens the margin or
halo will be bluish.
[Illustration: Fig. 4.]
These two aberrations, spherical and chromatic _were_ the principal
faults that opticians had to deal with, because they affect the
whole of the image, even the very central parts. But in photography
it is necessary to get an image of a very large size as compared
with the focal length of the lens, and there are some faults that
only begin to show themselves at a little distance from the centre
of the image and increase as the distance from the centre is
greater. These aberrations were, practically speaking, incurable
until a few years ago, but as recent optical advances have provided
kinds of glass by the use of which they may be eliminated, or nearly
so, they have become of practical importance. They are astigmatism
and curvature of field.
_Astigmatism and Curvature of Field._--If a diagram of suitable size
is made with a series of concentric circles and radial lines upon
it, and the centre of it is arranged exactly opposite the centre of
the lens, and in a line with the centre of the focussing screen, the
screen and diagram being parallel, then if the lens suffers from
astigmatism it will be found impossible to get the outer circles and
the radial lines where they cross them simultaneously focussed.
Where this difficulty begins the astigmatism begins, and the greater
the difference there is between the focal planes of the radial lines
and the circles, the greater is the astigmatism. It will probably
be found with any of the older types of lenses that neither is in
focus at the same time that the centre of the diagram is, but that
the screen must be racked in; this is due to curvature of field, and
the difference between the curvature of field for the circles and
the radial lines is due to astigmatism. In the older lenses a
flatter field could only be obtained by the introduction of
astigmatism, but now by the employment of the new glasses made at
Jena, it is possible to practically eliminate astigmatism, and still
keep the field flat.
[Illustration: Fig. 5.]
_The Development of Photographic Lenses._--When photography was
first practised the best lenses available were those made for use as
telescope objectives, and they had to be used with a small diaphragm
to get good definition over a sufficient field. With the slow
processes then in vogue a more rapid lens was much desired, and
Voigtlander introduced a "portrait" lens constructed according to
the results of the calculations of Professor Petzval. This portrait
lens is still very largely used, and figure 5 will serve to show its
general character and will be a guide to the putting of one together
correctly if it has been taken to pieces for cleaning. A rapid lens
such as this could not cover a sufficiently large field for
landscape work, so that single lenses were still used for work in
which rapidity was not of very great importance. Single lenses were
improved, and other kinds of lenses were introduced from time to
time, but it was not till 1866 that the "rapid rectilinears" or
"rapid aplanats," called later "rapid symmetricals," and by
innumerable other names according to the fancies of the makers, were
introduced. Probably no lens has been made in such large numbers as
this.
At about the same time, Dallmeyer introduced his portrait lens in
which the position of the convex and concave elements of the back
combination is reversed, the concave lens being outside, and this
gives the photographer the opportunity of screwing it back a little,
and so introducing a measurable amount of spherical aberration which
has the effect of modifying the otherwise exceedingly fine
definition at the centre of the field, and giving a greater depth of
definition.
In 1881, Messrs. Abbe & Schott began a series of experiments in the
manufacture of optical glasses, and they were so successful in making
new and useful varieties, that an optical glass factory was
eventually established at Jena, by Schott & Co. By the use of these
newer glasses the limitations that had previously restricted
opticians were removed, and it became possible to correct astigmatism
and secure a flat field at the same time. Zeiss of Jena, towards the
end of 1890, introduced his first series of "anastigmats." The
"concentric" lens of Ross was introduced in 1892, a lens which
probably remains unsurpassed for flatness of field and freedom from
astigmatism; but as spherical aberration is present to a notable
degree, an aperture of about _f_/22 is the largest that gives sharp
definition. The "double anastigmat" of Goerz of Berlin was put on the
market in 1893. It is a symmetrical lens, and in this different from
the Zeiss anastigmats that preceded it. It consists of two similar
combinations, each of three lenses cemented together. The unsurpassed
qualities of this lens stimulated other opticians to seek to rival
it, and there appeared similar lenses with four and even five lenses
in each combination, besides other lenses that are more or less a
copy of the double anastigmat. One of the most notable of these is
the "satz-anastigmat" of Zeiss, each combination consisting of four
lenses cemented together and forming an excellent single lens. These
combinations are interchangeable in the same mount so that with, for
example, one mount and three lenses, six different focal lengths can
be obtained, as the lenses may be used singly or any two together as
a doublet.
The "Cooke" lens is remarkable for the simple means by which the
various corrections are made, consisting as it does of only three
single lenses separated from each other. Obviously it must be used
entire. These lenses do not cover so large a plate in proportion to
their focal lengths as most of the other anastigmats, but perform
excellently over the plates for which they are constructed.
The "stigmatic" of Dallmeyer is the latest lens of general utility.
It gives good definition to the margin of the circle of light that
it transmits, reduction of aperture being necessary, when its full
field is employed, to get equality of illumination rather than to
improve the marginal definition. Its two combinations are different,
and either may be used alone as a single lens, giving focal lengths
of approximately one-and-a-half and twice the focal length of the
whole lens.
The "planar" of Zeiss introduced just as we write, is a symmetrical
doublet characterized by a very large aperture, from _f_/3.6 to
_f_/4 up to 10 inches in focal length, and a little smaller above
that. It is therefore comparable with portrait lenses. Although it
is symmetrical, a single combination cannot with advantage be used
alone as a single lens. Telephotographic lenses are subsequently
referred to.
The one aim of opticians in improving photographic lenses has been
to get good definition all over a comparatively large flat surface
without having to use small apertures. A defining power on the axis
of the lens, that is, at the centre of the field, far exceeding what
can be taken practical advantage of in ordinary photography, has
long been possible. But until recently, the defining power always
rapidly deteriorated as the distance from the centre was increased.
But to judge of the quality of a lens, or to compare one lens with
another, there are other matters that must be understood, and these
we shall proceed to consider. Focal length, aperture and image angle
are the chief details concerning lenses, granting that the
aberrations referred to above are satisfactorily corrected.
_Focal length._--The focal length or focal distance of a thin lens
is the distance between it and the point to which it converges
parallel rays. The rays of light are parallel when they issue from
an object at an infinite distance. For ordinary practical purposes,
any object, that is not nearer than a thousand focal lengths of the
lens may be regarded as at an infinite distance, that is the image
of an object so far off, and the image of the sun or stars (which
are situated at the nearest approach to an infinitely great distance
that we know of) would if separately focussed give an inappreciably
small difference of position of the focussing screen. But no
photographic lens is very thin. The measurement from the back
surface of the lens to the screen, when focussed on a distant
object, is called the "back focus," but this is of no use whatever
except as to the determining of the camera length necessary. The
"equivalent focal length" is the focal length (or focal distance) of
a thin lens that would give the same effect, so far as focal length
is concerned, as the lens in question. When the simple expression
"focal length" is used, it always refers to the equivalent focal
length. The single word "focus" is sometimes used erroneously
instead of "focal length."
The focal length of all lenses (except to a very small extent, with
single or so-called "landscape" lenses) is proportional to the
linear dimension of the image that it gives under similar
conditions. For example, a lens of 6 inches focal length will give
just the same amount of subject on a quarter plate that a lens of 12
inches focal length will give on a whole plate, because the linear
measurement of the whole plate is exactly double that of the quarter
plate. The easiest way to compare the focal lengths of two lenses,
is to focus both on a fairly distant object or view, and to measure
in the image the distance between two fixed points in both cases.
The proportion between these measurements is the proportion between
the focal lengths of the lenses. By this method the focal length of
any lens can easily be determined if one has a lens of known focal
length.
If a lens is first focussed on a distant object, and the focussing
screen is then moved back until the image of any object is of the
same size as the object, the distance travelled by the focussing
screen is exactly the focal length of the lens. It is however
exceedingly difficult to get at the same time an image of an exactly
predetermined size, and to secure the very best definition, so that
it is more convenient to get the image as near as it happens to come
to the size of the object and then to allow for the difference, as
then nothing interferes with the operation of focussing. The best
near object to use is an accurately divided scale, and the details
wanted in addition to those mentioned above are the comparative
lengths of the image and the object. To get these, two fine marks
are made on the focussing screen, and the distance between these is
the length of the image. The scale is focussed with critical
exactness and so that it falls over these marks, then the amount of
the scale represented between the marks can be measured, and the
divisions counted for the length of the object. The distance over
which the focussing screen was moved between the two focussings is
to be multiplied by the length of the object and divided by the
length of the image, and the result is the focal length of the lens.
_Aperture._--The "aperture" of a lens is the diameter of the
cylinder of light that it can receive and transmit. If the diaphragm
is in front of the lens, the hole in the diaphragm is the aperture,
but if the diaphragm is behind a part of the lens, so that the
incident light passes through a lens first, the hole in the
diaphragm is not the "aperture," the "aperture" is larger because
the lens condenses the light before it gets to the diaphragm. The
aperture of any lens can be measured by focussing a distant object,
then replacing the focussing screen by a sheet of cardboard with a
pinhole in the middle of it. In a dark-room a light must be placed
behind the pinhole, and a bit of ground glass held in front of the
lens. A disc of light will be seen on the ground glass and the
diameter of this is the diameter of the aperture, or simply, the
"aperture," with the diaphragm employed.
_Rapidity._--The rapidity of a lens depends almost wholly on its
focal length and aperture. The thickness of the glass makes a little
difference, and at every surface in contact with air there is loss
by reflection, but these and analogous matters are of comparatively
little importance, and as they are uncertain and cannot be
determined it is customary to refer rapidity to the focal length and
aperture only. The aperture found, that is, the diameter of the
effective incident cylinder of parallel rays, should be divided into
the focal length, and the diaphragm corresponding to the aperture
should then be marked with a fractional expression indicating the
proportion of aperture to focal length. Thus if the aperture is one
eighth the focal length, it is marked _f_/8, if a sixteenth _f_/16,
and so on. All lenses with the same aperture as so marked may be
regarded as of equal rapidity whatever their focal lengths may be.
Now the more rapid a lens is the shorter the exposure that it is
necessary to give for any subject, and the exposure required is
proportional to the square of the figure in the expressions as given
above. Namely 8 and 16 squared give 64 and 256 which are as one to
four, the proportional exposures required. Or we may say that 8 to
16 are as 1 to 2 and square these and get 1 to 4 the proportional
exposures.
[Illustration: Fig. 6.]
The best way to mark stops is, for example, _f_/8 and _f_/16, as
these expressions are universally understood, but some persons think
that the relative rapidities or intensities are better, others
prefer to express the relative exposure necessary, and every system
of numbering on these plans has a unit which is merely empirical,
not one of them adopting the only true or scientific unit of _f_/1.
Zeiss has recently changed his unit from _f_/100 to _f_/50.
Dallmeyer marks some of his lenses now with the practical
expression. The following table may be of service to those who
happen to have lenses with their diaphragms marked on any of these
empirical systems.
-------------------------------------------------------------------
| Royal | | | | |
| Photographic | | Paris | Zeiss | Zeiss |
_f_/ | Society. | Dallmeyer. | Congress.| (old). | (new). |
-------------------------------------------------------------------
3.16 | | 1 | 1/10 | | |
3.2 | | | | 1024 | 256 |
4 | 1 | | | | |
5 | | 2.5 | 1/4 | | |
4.5 | | | | 512 | 128 |
5.66 | 2 | | | | |
6.3 | | 4 | 4/10 | 256 | 64 |
7.07 | | 5 | 1/2 | | |
8 | 4 | | | | |
8.66 | | 7.5 | 3/4 | | |
9 | | | | 128 | 32 |
10 | | 10 | 1 | | |
11.3 | 8 | | | | |
12.25 | | 15 | 1.5 | | |
12.5 | | | | 64 | 16 |
14.14 | | 20 | 2 | | |
15.81 | | 25 | 2.5 | | |
16 | 16 | | | | |
17.32 | | 30 | 3 | | |
18 | | | | 32 | 8 |
20 | | 40 | 4 | | |
22.36 | | 50 | 5 | | |
22.6 | 32 | | | | |
25 | | | | 16 | 4 |
27.36 | | 75 | 7.5 | | |
31.62 | | 100 | 10 | | |
32 | 64 | | | | |
36 | | | | 8 | 2 |
38.7 | | 150 | 15 | | |
44.72 | | 200 | 20 | | |
45.2 | 128 | | | | |
50 | | 250 | 25 | 4 | 1 |
54.77 | | 300 | 30 | | |
63.25 | | 400 | 40 | | |
64 | 256 | | | | |
70.71 | | 500 | 50 | | |
71 | | | | 2 | |
100 | | | | 1 | |
-------------------------------------------------------------------
_Image Angle._--The image angle represents what is called covering
power. It may be expressed in terms of the focal length, and
doubtless this is the best method, but it is not customary. It may
be expressed as an angle, the angle formed when a line is drawn from
each extremity of a line equal to the diameter of the circle
covered, and caused to meet at a point distant from the base line
equal to the focal length of the lens. The angle where the two lines
meet is the image angle. But generally the covering power is
expressed more roughly, as the ordinary size of the plate that
sufficiently good definition can be obtained on.
_Tele-Photographic Lenses._--If a negative (or dispersing or
concave) lens is introduced between the ordinary lens and the plate,
the equivalent focal length of the arrangement is greater than that
of the ordinary lens alone, but the length of camera necessary is
not proportionately great. It is possible therefore to obtain an
image of a size that would otherwise require a lens of long focal
length and a corresponding and perhaps impossible length of camera.
But this is not the only advantage, for if the ordinary lens and the
negative lens are separable to a variable extent, the amount of
magnification of the image, or increase in the equivalent focal
length of the optical system, is adjustable at will. For further
details concerning tele-photographic lenses and their use, reference
should be made to Mr. Dallmeyer's pamphlet on the subject.
There are two other subjects connected with the production of images
by photographic lenses that must be referred to, though neither of
them is of great importance if we exclude the use of hand cameras
(which are separately treated of) and bear in mind the ordinary
practice of to-day. These are depth of definition and the distortion
due to the use of single lenses.
_Depth of Definition._--It has already been shown that the action of
the lens is to bring to a point in the image all the light that
falls upon it from the corresponding point of the object. Now it is
clear from fig. 2 that, if different parts of the object are at
different distances from the lens, and this must be the case with
solid objects, these different parts cannot be in focus at the same
time. Still it is possible to get them so nearly in focus that the
result is serviceable, and the ordinary method of doing this is to
examine the image on the ground glass, and if the whole subject is
not sharp enough, to reduce the size of the aperture. Depth of
definition is increased by using a lens of shorter focal length or
by reducing the aperture. If a large aperture has to be used, the
focal length must be short if much depth of definition is wanted, or
conversely, if the focal length must be long the aperture must be
small. It follows that very rapid lenses that have a very long
focus are of no use, for in portraiture, for example, this
combination of properties would lead to the ear in the image being
fuzzy if the eye was sharp.
If a lens were perfect and had a flat field, the depth of definition
would depend only on the aperture and focal length. But if the lens
gives inferior definition towards the edges of the field, it is
quite obvious that there must be less depth of definition there, if
a minimum of defining power is accepted. The definition at its best
may be inferior to the minimum accepted and then obviously there is
no depth. Depth of definition therefore at the centre of the plate
depends entirely on the focal length and aperture, but away from the
centre it depends also on the quality of the lens, and is much
greater in a flat field anastigmat than in a lens of an older type.
But depth of definition is not a quality apart, it depends entirely
upon other factors, and it is better in examining a lens to
determine these factors separately rather than to lump them together
as depth.
_Distortion_ produced by single lenses is due to the fact that the
diaphragm is either in front of or behind them. If the diaphragm is
in front, the image is drawn towards the centre of the plate to an
extent that increases as the margin of the field is approached. A
line along one side of the plate has its ends drawn in to a greater
amount than its centre, because they are further from the middle of
the plate, and therefore it becomes curved like the side of a
barrel, and this effect is called barrel-shaped distortion. If the
diaphragm is behind the lens, the displacement is outwards, also
increasing towards the edges of the field, and a straight line at
the edge of the plate becomes curved so that it is convex towards
the centre of the plate. This is known as hour-glass distortion.
Both these effects are illustrated (and exaggerated for clearness'
sake) in fig. 6, the central square representing the true figure.
This "curvilinear distortion" is absent in all cases in the middle
of the plate and generally for a considerable area, and if single
lenses of only long focal length are used, say of a focal length
equal to at least one and a half times the length of the largest
side of the plate, it may be neglected. Wide-angle single lenses
should never be used except on a suitably small plate, so that the
above conditions hold. The nearer the diaphragm is to the lens the
less is the distortion, and some of the most modern single lenses
have the diaphragm so near that the photographer is even more safe
in the use of them.
[Illustration: MELTON MEADOWS. A. HORSLEY HINTON.]
_The Comparison and Use of Lenses._--The optician when he tests
lenses looks for each fault individually, but this the ordinary
photographer is hardly able to do, nor is it particularly desirable
for him, because if a lens is inferior it matters little to him why
it is so. On the other hand occasion may arise when he wants to
identify a fault, then the information already given will probably
be sufficient to enable him to do so, if to it is added that a small
pinhole with a flame behind it is a convenient point of light, and
that if the image of this luminous point is examined with a good
eyepiece, without the focussing screen, at various parts of the
field, the character of the defect may be discovered.
The main things that the photographer needs to look to in judging of
a lens or comparing it with another, are (1) that it works to focus,
(2) the quality of its defining power especially towards the edges
of the plate. There must also be taken into account the focal length
and aperture, and if both these are not the same in the lenses to be
compared they should be nearly the same, and the proportion that the
aperture bears to the focal length should be exactly the same. A
special diaphragm may have to be cut out of card for one of them.
The best test object that is always at hand is a newspaper pinned
flat against a flat wall. The camera must not be moved during the
work. Each lens is very carefully focussed and a negative made,
using the same aperture, time of development, and in all ways
similar treatment for both. If the focal lengths are different, the
images will be of correspondingly different sizes, and then the same
detail must be compared, not the definition at the same distance
from the centre.
All good lenses work to focus, but some of the cheaper ones do not.
To test this, any series of small objects arranged side by side, but
at distances varying by intervals of say two inches from the camera,
is photographed after carefully focussing on the middle one. If any
other than the middle one is the best defined, the lens is at fault.
But in this, as in all similar tests, it must be remembered that
ordinary dry plates are not quite flat, and the error of the plate
may make an appreciable difference.
The use of lenses comprises the whole art of working with the
camera, it is therefore not our province to say much about it. But
so far as lenses themselves are concerned it may be remarked that,
if a lens has a round field, it may be advantageous to tip up the
lens with regard to the plate when only a part of the plate is being
used, as for example sometimes in taking a landscape. But in using
the modern flat field lenses special care should be taken to keep
the lens and plate exactly true to each other, the plate exactly at
right angles to the lens axis. The image and plate must coincide or
definition will suffer. If the image is rounded and the plate flat,
then in any case the result is only a compromise, but to take full
advantage of the larger apertures when the field is flat, much more
care than has been usual must be devoted to this matter.
_Simple uncorrected lenses_ such as _spectacle lenses_ or
"_monocles_," suffer from the defects that have already been
described, and are valued on this account by some workers because
they give blurred or "soft" images. With a small enough diaphragm
they will give good definition, and generally it may be stated that
reducing the aperture lessens the effect of any fault that a lens
may possess. To get the best definition that a simple lens will
give, the plate must be brought nearer the lens after focussing by
about one-fiftieth of the focal length of the lens, so that it may
be brought from the best focus of visual light into the best focus
of the photographically active light. If the object photographed is
nearer to the lens than about one hundred times its focal length,
the amount of movement after focussing must be increased. If four
focal lengths distant, the correction is nearly one-thirtieth of the
focal length, at three focal lengths distant, nearly one-twentieth,
and at two focal lengths, about a thirteenth.
_Pinholes_ give an image that for all practical purposes may be said
to be equally blurred or "soft" over the whole plate. Much has been
written about pinholes and their use, but it is not definitely known
yet whether the exposure should be longer or shorter than the
exposure required when a lens is used, allowing, of course, for the
smallness of the aperture. The following short table and exposure
rules from the writer's "Science and Practice of Photography," will
probably prove useful:--
+----------------------------+------+------+------+------+------+
| Pinholes--diameters | 1/16 | 1/22 | 1/32 | 1/45 | 1/64 |
+----------------------------+------+------+------+------+------+
| Distance from plate for | | | | | |
| sharpest image ... | 64 | 32 | 16 | 8 | 4 |
+----------------------------+------+------+------+------+------+
All the above figures are in inches. Whatever pinhole and at
whatever distance, estimate the exposure for a lens at _f_/16,
_f_/22, _f_/32, _f_/45, or _f_/64, as the case may be, and multiply
it by the _square_ of the number of inches that the plate is distant
from the pinhole. But if the distance is as given above for any
hole, it is sufficient to expose for as many minutes as the plate is
inches distant from the hole, for a subject that would require one
second with an aperture of _f_/16.
_Chapman Jones._
_Portraiture._
[Illustration]
The photographer who may be expert at landscape or architectural
work, will find himself at a loss when he essays portraiture. For
apart from the art of managing the sitter (a most important element
in producing a successful result), he will soon find that the kind
of plate that is suitable for outdoor work does not answer well for
portraits, unless the developer is greatly modified, for quite a
different kind of negative is required. As a general rule it is
advisable to use very rapid plates for portrait work; and in this
respect, at the present day we are much better supplied than even
five or six years ago, and with an extra-rapid plate it is possible
to secure a fully exposed negative in half a second, in weather and
under lighting that was quite impossible ten years ago. The best
expression and pose are generally secured when the sitter is unaware
of the actual moment of exposure; and for this purpose a silent
shutter working inside the camera is best. The sitter should never
be _asked_ to keep still unless, in groups, and when circumstances
necessitate a long exposure; and nowadays an exposure of five or six
seconds is a long one. Every effort should be made to put the sitter
quite at ease.
A head-rest should not be used unless absolutely necessary, and few
photographers are aware how easily it can be dispensed with, and
fail to realize how strong an objection nearly every sitter has to
it. It is far better to have an occasional plate spoilt by working
without the rest than to make every sitter uncomfortable by its use.
In fact some portrait negatives are actually improved by a slight
movement. In a special kind of lighting when the face is in _shadow_
relieved against a light background, a slight movement which
produces the effect of diffusion of focus greatly improves the
result.
Great care must be exercised in choosing the background even when it
is only plain or graduated, and it is well worth exposing three or
four plates on the same sitter, in the same position and lighting,
and with the same exposure, but with different backgrounds, and then
carefully comparing the resulting prints. Even if only one
background is at hand its depth can be varied by placing it nearer
or farther from the source of light. The background must also be
selected to suit the lighting of the sitter, as a background of
medium tint suitable for what is called "ordinary lighting" would be
quite unsuitable for "Rembrandt" effects, or where strong contrasts
of light and shade are used, when part of the face is in dark
shadow. For such effects a dark background is usually best, as it
gives luminosity to the shadow side of the face. But such dark
grounds are not suitable for "ordinary lighting" where the face
should be full of delicate half-tone, all of which would be killed
by the strength of the dark background.
For the Rembrandt effects a much longer exposure is necessary as
less light is reflected from the face on to the sensitive plate;
they will often need twice or three times as much as for ordinary
portraits.
When pictorial backgrounds or accessories are used it must be
remembered that the object of the photograph is to secure a portrait
of the _sitter_, not to show what a large stock of accessories the
photographer possesses. It is best to use as few accessories as
possible; I have heard a lady complain bitterly of a well-known
photographer, who having posed her in a very difficult position,
kept her waiting for five minutes while he arranged a screen, a
palm, a footstool, a tiger-skin, etc., so that she felt positively
ill before the exposure was made. The sitter should not be kept
waiting in the pose to be photographed any longer than is absolutely
necessary. If accessories must be used they should be simple and
suitable.
When portraits have to be taken in ordinary rooms it is advisable to
get a friend or assistant to experiment upon, if possible
beforehand. Even a few minutes spent in studying the possibilities
of light and arrangement of furniture will save a great deal of
worry when making the actual exposures, and nothing upsets nervous
sitters more than having all kinds of experiments and arrangements
made with them. But it is sometimes well worth wasting a few plates
on exposures which the photographer thinks will be useless, in order
to give the sitter time to get accustomed to the room; it must not
be done in a fussy, irritating way, but rather to show that it is
not such a very dreadful operation and really "doesn't hurt." This
plan often works well with nervous children, who soon become
accustomed to the room and the photographer. There is a great deal
to be said in favour of the maxim "leave your sitters alone." The
photographer must cultivate quick observation so that he sees at
once a good pose, and secures it; and here again quick plates are
essential, as many of the most charming poses are caught
unexpectedly. It has been well said that the best poses the
photographer secures are those he _observes_, not those he
_creates_. But a spontaneous pose may not be quite perfect and a
slight alteration may be easily made without disturbing the rest of
the figure. It will generally be found that a pose that takes a
great deal of arranging is not a success.
When taking portraits in an ordinary room it is usual to place the
sitter near the window, so that one side of the face is strongly
lighted and the other in deep shadow, and then use a white reflector
to light up the shadow side. It is often better, when the window is
a large one, to place the sitter farther back in the room almost
facing the window, and put the camera near the middle of the window
looking into the room; a softer lighting will then be secured. For
outdoor portraits a shady corner is best, and if possible, one where
the side light is much subdued on one side; a light head-shade may
be used with advantage. A large grey rug out of focus makes a good
background; a blanket is too light.
A portrait lens is best for the work; but if the photographer does
not possess one, he need not despair of producing good work. A rapid
rectilinear lens used at a large aperture will answer the purpose
well; it should always be used at full aperture, partly for the sake
of quickness in exposure, and partly to prevent accessories and
parts of the dress appearing too sharp and competing in importance
with the face. Subordination of parts is one of the essentials of a
picture; and if we examine a _good_ portrait we shall find that
probably no part of the photograph is quite sharp except the eyes
and face. Otherwise the less important details are apt to obtrude
themselves on our notice. A stop will generally be necessary,
however, with a portrait lens if a full or three-quarter length is
to be taken, and it will be found that heads only (as a rule) can be
taken at full aperture. Just as good work, however, can be done with
a rapid rectilinear as with a lens specially made for portraits,
except where rapid exposures are to be made; but it is necessary to
use one of fairly long focus. A rapid rectilinear lens used for
landscape work on a half plate would be much too short in focus for
giving good portraits on the same sized plate, for in order to get
the figure large enough it is necessary to place the camera so near
the sitter as to produce distortion. For portraits on a half plate a
lens of at least nine inches focus should be used and for a whole
plate not less than sixteen or eighteen inches, and longer if
possible.
The swing back of the camera will be found useful in portrait work
for getting parts of the figures into focus that are either too far
behind or too far in front of the plane of the face. For instance, a
full-length figure leaning back in a chair will have the feet out of
focus when the face is sharp if the back of the camera is vertical,
and this applies with even greater force to groups. A side swing too
is useful, but is not absolutely necessary. Even in bust portraits
the swing back is useful in getting the shoulders in focus when
using a large aperture, for although it is well not to have the
whole of the figure in _perfect_ focus all over, it is not advisable
to have the face sharp and the rest so out of focus as to be
blurred.
The development of a portrait plate should be different from that of
a landscape, because a different kind of negative is required. A
rapid plate developed so as to give a soft delicate image is best;
and a developer containing more alkali and less density giver is
good, and it may be considerably diluted with advantage. The image
should appear within ten seconds of pouring on the developer, and
the negative will generally be developed to sufficient density in
from two to three minutes. With a good average rapid plate the image
should show fairly well on the back of the plate, but this and the
time of development will vary so much with different developers, and
with the taste of each photographer that no hard and fast rule can
be laid down.
Developers that give a brown deposit, or that stain the film will
require shorter development than those of the newer developing
agents that give a cold black colour to the negative; another fact
to be borne in mind is that the image formed by these latter appears
to lose more density in fixing than when pyrogallic acid is used.
A perfect portrait negative should have no clear glass shadows, and
no part should be so dense as to give white in the finished print,
and some negatives which give the best results may have a decided
veiled appearance in the shadows.
The temperature of the developer is another important point; in very
cold weather the developer should be kept warm, or if in
concentrated solutions may be diluted with warm water. In cases of
known under-exposure the developer may be used quite hot with
advantage. A convincing experiment can be made by cutting an exposed
plate in two and developing one half with icy cold developer and the
other half with warm. The difference is really remarkable. If the
developer has been used hot enough to make the gelatine of the plate
feel "slimy" an alum bath is necessary, unless the fixing bath
contains chrome alum.
METOL.
1.
Water 100 parts or 10 ozs.
Metol 1 part or 50 grains
Sodium sulphite 10 parts or 1 oz.
2.
Water 100 parts or 10 ozs.
Potassium carbonate 10 parts or 1 oz.
3.
Potassium bromide 1 part or 1 oz.
Water 10 parts or 10 ozs.
For normal exposures take 3 parts No. 1 and 1 part No. 2; to each
ounce of mixed developer add 40 minims of No. 3.
PYRO AND SODA.
1.
Pyro 1 oz.
Water 70 ozs.
Nitric acid 12 drops
2.
Sodium sulphite 10 ozs.
Sodium carbonate (pure) 8 ozs.
Water 70 ozs.
Equal parts of each, for soft negatives dilute with water. To
restrain for over-exposure use potassium, not ammonium bromide.
Unless an acid fixing bath is used the negatives are rather green in
colour.
RODINAL AND HYDROKINONE.
A.
Sodium sulphite 1 oz.
Water 20 ozs.
Citric acid 1 crystal
Potassium bromide 1 dram
Hydrokinone 2 drams
B.
Potassium carbonate 2 ozs.
Water 20 ozs.
Rodinal 1 fluid oz.
Use 1 part A, 1 part B, and 1 part of water.
The question of retouching is a difficult one. There is no doubt
that a certain amount of it is necessary on nearly all portrait
negatives and even on those of children. But it is equally certain
that the great majority of portrait negatives are over-retouched, so
much so that their value both as portraits and pictures is nearly
destroyed. Yet a certain amount is necessary even for pictorial
effect, and perhaps still more when the question of likeness is
considered. For as a rule the untouched negative is no more a true
likeness than the over-retouched one. The truth lies somewhere
between the two. Even if isochromatic plates are used the little
differences of colour in the face, and the incipient wrinkles are
exaggerated in an unpleasant way. Under-exposed negatives will show
these defects in a very marked manner, full exposure will greatly
reduce them. Large heavy patches of shadow may be lightened by
coating the back of the negative with matt varnish, and when it is
quite hard "hatching" upon it with a soft lead. Harsh lights may be
reduced by scraping away the matt varnish with the point of a knife.
In some cases the matt varnish may be stained with a little aurine
or uranine. Exaggerated lines and small shadows must be worked upon
from the front and a retouching desk is necessary. The film of the
negative will not take the pencil without some preparation. The best
surface is obtained by spreading a little retouching medium with the
tip of the finger on the part to be touched. A thin film of soft
resin is left upon the plate which takes pencil marks readily. A
hard lead, No. 4 Faber or Hardtmuth, should be used. The loose leads
used in what are called the "ever-pointed holders" are most
convenient. The point must be very long and fine, like a large
darning needle, and is best made by rubbing the lead on a piece of
fine glass-paper. The pencil must be held very lightly and the lines
touched away with short _light_ strokes, a heavy stroke only rubs
the medium up.
The little shadow at the end of the mouth often has to be reduced,
often at the risk of spoiling the shape of the lips, but sitters
_will_ insist upon it being done, and say "You have made my mouth
much too large." Freckled faces are perhaps the most difficult to
retouch, as it is well nigh impossible to remove the black patches
caused by the freckles without at the same time destroying the
modelling of the face. Yet it must be done, for probably the most
severe stickler for truth would not insist on the black blotches
that freckles produce in a photograph.
A great deal can be done to improve a hard negative as soon as it
leaves the fixing bath, by applying a mixture of hypo solution and a
solution of ferricyanide (not ferro) of potash with a piece of cotton
wool to the dense parts. The proportions for this reducing bath are
as follows:--To each ounce of the ordinary hyposulphite of soda
fixing bath add a few drops of a 10% solution of ferricyanide of
potassium or red prussiate of potash, making the whole about the
colour of pale brandy. By adding more of the ferricyanide solution
the reducing action is quicker, but there is a greater liability to
stain the film. The work should be done over a sink with a tap of
running water at hand. The solution should be of a deep lemon colour
(it is almost impossible to give exact quantities), and after a short
application must be washed off under the tap, and the negative may
then be examined, and the reducer applied again and again till the
desired reduction is obtained. It is advisable to make a few trials
on spoilt plates. For if any really good work is to be done there
will be plenty of rejected negatives. Probably, of all the plates
exposed on portraits by first-rate professional photographers, not
more than one-fourth ever get as far as the printing-frame.
Moral: Do not be chary of exposing plates, they are cheap enough
now. Don't feel, "Oh! this will be good enough. I won't do another."
On the other hand don't expose carelessly and recklessly and say,
"It will all come right in developing." Good work is not done that
way. Use every opportunity of seeing good work. Study the work of
great portrait painters, but don't neglect the photographers. Go to
all the exhibitions of pictures and photographs within reach.
Don't be satisfied with what you have done, but make a resolve to do
something better next time. Remember, what is worth doing at all is
worth doing well.
_Harold Baker._
[Illustration: Off Boulogne. By A. Horsley Hinton.]
_Pictorial Photography._
[Illustration]
Unlike the subjects of the other articles in this book, in pictorial
photography we are not brought to consider one of the many processes
which go to make up the photographic craft, but merely a special and
exceptional application of any and all means known to the
photographer.
The particular end to which this application is made will be
explained as far as the limits of space will permit, and some of the
methods of such application will be described. Beyond this I have no
intention of going. I do not present pictorial photography as a
branch of photography especially worthy of study--I am not concerned
in making converts. It is for the photographer who has already
formed a desire to give his attention to the pictorial side of
photography and who is seeking help, that this chapter is designed.
First let us come to a mutual understanding as to the term Pictorial
Photography. Picture-making by photography would perhaps be a
simpler phrase, but that to my mind the word "picture-making" is too
similar in idea to boot-making, lace-making, etc., all of which
imply a mechanical manufacturing, whereas a picture--a real
picture--like a musical composition, a poem or a beautiful thought,
grows or is evolved rather than made to order.
Art photography would be a better term, but that in photography the
word "art" has been so often coupled with things the very antithesis
of artistic and might hence be misleading, moreover the photographer
will show discretion rather than weakness if he be not too hasty to
claim for photography a position among the arts, and whilst its
claims to that dignity remain as yet in dispute, we may be content
with "Pictorial Photography" as a less assuming title, yet one which
will sufficiently differentiate between what we may call the
ordinary photographic production and---- Well, what?
That is the first thing I have to try and explain.
Look at the illustrations in this book on pages 72, 136, and 120,
and, making due allowance for some loss of quality due to
reproduction by a "half-tone" block, try to imagine what the
originals were like. Then say if they please you. If you say no, you
do not care for them, they do not appeal to you, you do not mind if
you never saw anything of the kind again from this day henceforth;
very well, doubtless there are other things in the world in which
you can find pleasure, but so far as my present subject is
concerned, here you and I part company. These illustrations are more
or less successful reproductions of pictorial work, and if you do
not like them, making as I have said due allowance for their being
reproduced and reduced, then it is certain you do not want to hear
anything about them, and it is not my intention to persuade you, so
please pass on and make room for those who do care for these things
and wish to learn all they can concerning them, or at most stand
aside and peradventure some stray word dropped unintentionally may
quicken your interest and discover in you a sympathy of which you
were previously unconscious.
[Illustration: MISS LILY HANBURY--A PORTRAIT. HAROLD BAKER.]
Referring now again to the illustrations which in the absence of
anything else we take as fairly typical of pictorial photographs and
assuming that one or the other, if not all, do please some of my
readers, I will ask them to endeavour to analyse their feelings when
confronting such productions.
Take now an ordinary commercial photographic view such as one may
purchase from any sea-side stationer, and compare the sensations
awakened by each. In the case of the topographical view we feel some
satisfaction at being able to recognise a familiar spot, or the view
reminds us of some other place, or it may be quaint buildings, or
rugged mountains, or miles of foliage, or what not inspire curiosity
or interest because we know the photograph to be a true record of
facts, that is to say we accept the photograph in lieu of the actual
presence of the objects represented, and experience nearly the same
feelings as we should were we to visit the spot represented. We know
that the wonderful, curious, or unusual things portrayed have an
existence, otherwise we could not have a photograph of them.
In all such cases our interest and value of the photograph would
vastly diminish, were it possible for a photograph of this kind to
be made simply by the photographer's hand and imagination without
any original at all.
You look at a photograph of this or that sea-side place and remark,
"Ah, yes, that's dear old Yarmouth, many a time, etc., etc.," or
else, "Dear me, I wonder what place that is, it's so like----" such
and such a town, or it may be you enquire "Where's that?" and you
express or think to yourself you would like to go and visit the
spot. These and kindred sensations are those kindled by the average
photograph, but there is yet another, for you may be impelled to
exclaim, "How wonderfully clear and bright that photograph is,"
"What a good photograph." In this case you are interested purely in
the execution as an example of clever manipulation and skilful
craftsmanship.
Now, compare such feelings as these with those stirred by an example
of good pictorial work. In the first place your esteem for it, if
you value it at all, is quite as great whether you know the place
where it was made or not. If it pleases you, that pleasure is not
dependent upon the fact that it does represent some place. In the
case of paintings and drawings as often as not they do not pretend
to represent any place at all, but are pure fiction, yet we do not
value them the less. To what then is the pleasure we feel when
looking at a good picture due? Is it not that a picture stirs up,
that is, _creates_ pleasant or beautiful thoughts and ideas--by
pleasant I do not mean necessarily merry or joyous ones, for some
hearts feel profounder pleasure in the grandeur of storm or the
majesty of the mountain than in the sweet wilderness of flowery
wastes, but notice that such beautiful ideas are _created_ by the
picture. You were thinking of something totally different before you
came upon the landscape picture which instantly made you feel the
glowing light, the stirring breeze, and hear the rustling corn and
noisy brook, and yet it cannot be said it is because we _recognise_
these things in the picture that we receive these impressions, at
least it is not the kind of recognition which takes place when we
see a photograph of Brighton Pier or Haddon Hall.
Notice, it is not the exact and faithful portrayal of objects that
creates the emotions instanced, for if you closely observe the
manner in which a good painting is done you will find that rude
splashes of paint, broad brush strokes, and the like stand for
foliage or water, or corn stalks as the case may be, when we know
that had the painter desired he _could_ have produced his likeness
of nature with a good deal more of the precise detail and fidelity
to outlines which photography excels in, _had he wished_. But if the
painter or other pictorial artist needs not to trouble about
accuracy to details to secure the effect aimed at he must be
faithful to general facts. There is a great difference between not
recognising things or having no particular wish to do so, and
feeling conscious that a portrayal is so utterly unlike anything in
our past experience of nature that we should not recognise the
objects even if we _were_ acquainted with them. To take an extreme
case--our enjoyment of the effect and sentiment of a beautiful
landscape picture is not enhanced by our being able to recognise
whether the trees are oaks or elms, but it would be distinctly
disturbed if the palm trees were represented as growing on the
slopes of a Welsh mountain. Innumerable examples and instances might
be given to show that the artist, whatsoever his medium, be it
colour or monochrome, may depart from truth, or may be indifferent
to precise details, _only so far as he avoids palpable untruth_.
Why is this?
When we look at a powerful and impressive picture we feel at once
the sentiment, our emotions are at once stirred, subsequently we
recognise objects and facts portrayed, but only when we begin to
look for them or think about them; but a gross exaggeration or a
very obvious error strikes us at once before we begin to receive
sentiments and ideas, and that error or exaggeration once seen is
never lost sight of, and whole enjoyment of the picture is
hopelessly marred.
Now, from the foregoing (for want of space I am aware that the
argument is incomplete, and must therefore ask the student to think
the matter out and grasp the side issues by reading between the
lines) we may formulate the broad definition that a picture does not
depend for its excellence on the faithful representation of objects,
and is not chiefly valuable on account of our immediate recognition
of things portrayed, yet on the other hand it must not let us feel
that there is obvious inaccuracy.
Here then we have two opposite positions in both of which the mere
objects employed to build up the picture are subordinated to the
effect or impression of the picture. In one case the spectator must
not be allowed to feel that the representation is _wrong_, in the
other success will not directly depend on the representation being
very _right_, neither startling rightness or truth nor the obvious
wrongness or untruth should thrust the objects composing the picture
upon the beholder's attention, he should be left free to receive the
expression or sentiment of it.
I hope the reader is following me in this line of thought closely. I
am aware that it may seem dry and uninteresting, but I see no other
way of placing the student in a proper position at the outset than
by explaining the essential elements of pictorial work, and I will
make this introductory part as brief as possible.
Reverting now to our argument, I have in other words suggested that
obvious violation of truth will prevent the sentiment or effect of
the picture from being paramount, and now I will submit that an
excess of accuracy to detail is equally detrimental to the success
of a picture as a picture.
If by now the reader is prepared to admit that the chief purpose of
a picture is the feelings, emotions, ideas which it suggests or
creates, and not the facts it portrays, he will be able to go
further and perceive that in a landscape, for instance, cottages,
trees, or what not are introduced, not for their own intrinsic
interest but as vehicles of light and shade, which go to express the
picture's sentiments.
If we stand before a good picture with closed eyes and suddenly open
them, our first impression (precluding any question of colour) is
that of masses of light and shade pleasingly and harmoniously
arranged; if we retreat to such a distance that the objects
constituting those lights and shades are unrecognisable the balance
and pleasing arrangement should still be felt, and our æsthetic
sense is satisfied, although we do not see fully of what the picture
is composed. This is the quality which is termed breadth and which
is admittedly of very great value.
If on the other hand the shadow masses are filled with innumerable
details, and are thus broken up into tiny lights and shadows they no
longer exist as broad masses of dark, but if before retreating as
proposed from the picture, the lights or shadows appear so blank as
to prompt particular investigation, and upon examination we find
detail absent which we know must have been present, then we
encounter an instance of untruth and exaggeration which is obvious
and which disturbs our appreciation of other fine qualities. Thus we
require _sufficient detail to avoid giving the idea that detail is
left out_.
The delineation of sharp outlines and redundance of detail is not
wrong in itself, but it is usually inexpedient when considered with
respect to the effect to be produced, similarly the suppression of
sharp focus both as regards outlines and details has no artistic
merit of itself except as it assists the picture to impress the
beholder first with the general effect.
The painter and photographer start from two opposite standpoints.
The painter, or draughtsman, starts with nothing but blank paper,
and having built up his picture and produced his desired effect he
elaborates no further; the photographer with his more or less
mechanically produced _facsimile_ starts from the opposite extreme
with a transcendentally elaborate image, from which he will require
to eliminate all such excess of truth as is likely to force the mere
facts of the view upon the beholder's attention.
Photography, so faultlessly complete in its delineation, gives us
_more than the pictorial worker needs for the expression of an
idea_, and this is why I would remind the student that pictorial
photography is not photography in the full sense of the word, but
the application of some of its powers, just as much as we need and
no more, to a definite end.
As just hinted the purpose of a picture is to express ideas, hence I
will fall back on a kind of definition which I have used on a
previous occasion that a picture is the portrayal of visible
concrete things for the expression of abstract ideas.
To give an example by way of exposition we may look upon a picture
and be made to feel by it the calm and luminous atmosphere of
evening; we feel at once the restfulness, and almost feel the warmth
of the humid air, giving place to the chill gathering mists of
night; but the same objects, the same tangible materials, paper,
pigment, metallic salts, etc., in another picture give us the sense
of angry turbulent storm or perhaps bright joyous sunshine
frolicking with the fresh breezes on the hill-tops. These are
abstract ideas expressed or created by the manner in which concrete
things, commonplace facts, are portrayed and rendered.
Finally, let me enunciate that a very excellent photograph may not
necessarily be a good picture, because it may contain more than is
required for the expression of its idea, and the surplus will
overwhelm it; again, a good pictorial photograph may be but a poor
photograph, because if we claim the right to apply photographic
means to pictorial ends, we may find it convenient to leave out the
very qualities which the scientific or technical expert considers
most precious.
And now I think we may proceed to more practical matters.
COMPOSITION AND SELECTION.
In all matters from which the eye expects to derive pleasure,
symmetry of design seems essential. In the formation of the letters
that we write, in personal attire, in the decoration of our homes,
in buildings, and practically in everything which is not of a purely
utilitarian character, a sense of proportion and a symmetrical
disposition of parts is observed. Hence it is no source of surprise
that in a picture which as much as anything should aim at pleasing
the eye, design, otherwise Composition, is with Expression a
co-essential.
In a purely decorative production this natural desire of design is
the only thing to be observed, but in a picture which _may_ be
decorative, but _must_ be something more, we have expression as well
to consider. If decoration alone were to be regarded, something like
fixed rules might perhaps be tyrannically laid down, but in a
picture the implicit observance of rules of composition would be
certain to make itself seen in the result, and the undue
obtrusiveness of a code of rules would be as inimical to the
supremacy of ideas and feelings, as the excessive prominence of fact
would be, which has already been described.
Hence the difficulty in prescribing any definite course for the
beginner, because whilst to most instinctive artistic temperaments a
certain knowledge of or feeling for composition is natural, so soon
as this is reduced to definite rule and given to another, the, as it
were, secondhand use, is nearly certain to betray itself by its
misapplication. I would ask therefore that any suggestions given
here on the subject of composition should be taken as one takes
lessons in the rudiments of a language, which rudiments we violate
and forget so soon as we have become proficient enough to speak it.
_Such rules in composition should be observed only so far as to
avoid the appearance of having infringed or ignored them._
The rules of composition which may be found to apply in one of the
pictorial arts must necessarily apply equally in the others, and so
therefore to pictorial photography which at least aspires to be
considered an art. If on a sheet of paper a rectangular space is
given us wherein to draw the likeness of anything, the most natural
course to pursue would be to draw that figure in the centre or
thereabouts, and if then we are asked to add the likeness of two or
three more objects we should naturally place these near the first
object. Thus should we compose a group of objects which draw the
attention to the middle of the picture or space.
Suppose we are asked to draw the picture of a church tower we should
probably comply with the request somewhat as shown in fig. 1. Next
we will suppose we are asked to add a cottage, some trees, and a
path to the church, we should, if possessed of some sense of
symmetry and order, coupled with average intelligence, make the
additions somewhat as in fig. 2. It would surely be an unusual thing
to follow instead the course suggested by figs. 3 and 4.
In figs. 1 and 2 we have instinctively placed the primary object in
or near the centre, and the others near and around it, and the
result strikes one at once as being better composed, that is, more
symmetrical, than in fig. 4, in which amongst other things one is
not sure which object to regard as the principal one, and one also
feels that but for the boundaries of the picture left and right we
might have seen a good deal more beyond, which would have added to
the interest of the picture.
[Illustration: Fig. 1.]
[Illustration: Fig. 2.]
[Illustration: Fig. 3.]
[Illustration: Fig. 4.]
In this we have one of the first rules in composition, namely, that
the principal object should be near the centre, and the next
important near to, and as it were supporting it, and no object
likely to attract the eye should be so near the edge of the picture
as to make us instantly conscious of the boundaries and wish to see
more beyond.
But now if in compliance with the supposed request we had made our
drawing as in fig. 5, might it not at once be felt by the observer
that we had put the objects in a central position _intentionally_,
which is equivalent to saying that we had allowed our endeavour to
observe the rule just laid down to betray itself. Fig. 2 is
preferable as being only just sufficiently symmetrical to avoid
being unsymmetrical, which is an example of what has already been
said about the necessity of observing rules of composition just so
far as to escape the appearance of having broken them.
[Illustration: Fig. 5.]
[Illustration: Fig. 6.]
If this rule is right as regards voluntarily drawing a picture, it
is equally so in the case of a photograph, but instead of
deliberately placing things in such and such positions, we attain
the same end by moving the camera and selecting our point of view so
that the objects come into the positions desired.
Now suppose then, we have done this, but in doing it we are quite
unable to prevent other objects coming into the field of view and
occupying undesirable places near the margins of the picture, as for
instance in fig. 6. Here we are brought to consider another rule or
principle in composition, namely, that there must be one and only
one chief object in the picture, whereas in fig. 6, apart from the
gate and tree on the one side and the windmill on the other
attracting attention to the margins of the picture, these same
objects arrest the attention quite as much as the church, and we
feel the eye wandering about from one to the other and missing the
sensation of centralization and rest which fig. 2 gives.
If we were drawing or painting we should put in what we want and
then stop, we should omit or ignore what we did not require, but in
photography our powers in this direction are limited, and hence we
must as far as possible select those views, and only accept such, as
comply with what we feel to be right.
The angle of view included by different lenses is an auxiliary not
to be neglected, for by substituting a narrower angle lens, that is,
one of longer focus, we may cut off or leave out undesirable objects
which the shorter focus lens might include. Then again, when the
print is finished we can after careful consideration cut off what
would have been better left out, for it will be better to have a
picture half the size well composed, than double the number of
inches with a distracting and unsatisfactory arrangement of objects,
hence with many most successful workers it is no uncommon thing to
take quite a small portion of a negative, and either print it as it
is or else enlarge it up to the desired size, but mere size will
reckon as nothing as compared with pleasing composition.
If it is inexpedient to let the principal object or group of objects
occupy the exact centre of the picture, measured from left to right,
it is equally so if the centre be measured from top to bottom, and
hence we may formulate the rule (to be broken perhaps later when we
are strong enough to be independent of guiding) that the horizon
should not be allowed to come midway between the top and the base of
the picture.
[Illustration: Fig. 7.]
[Illustration: Fig. 8.]
Remembering now that, as set forth in the earlier part of this
article, a picture should appeal to our feelings and stir our
emotions, it may be pointed out that in most ordinary things, and
certainly in the arts, the most powerful things are those which
possess _one_ dominant idea or feature, as in a piece of music the
refrain keeps recurring, a preacher takes a text, in a story there
is _one_ hero, and so forth, and in point of composition fig. 7 is
better than fig. 8, although the view is less comprehensive.
[Illustration: Fig. 9.]
It may not, however, always be easy for the beginner to determine
what is the chief object which should occupy the central position,
or which object or group to choose in a landscape.
[Illustration: Fig. 10.]
This brings us to speak of another important matter, and that is the
right disposition of lines which form the view or the selection of
view so that the lines formed by the component parts shall fall in a
desirable manner. The various objects in any view tend to form or
suggest lines, thus in fig. 9 the outline of the trees, the bank
along the shore, the clouds, and the boats suggest the lines shown
in the diagram, fig. 10, which lines all run the same way, but in
fig. 11 we have a similar view in which the lines suggested
counterbalance each other, and not only so, but by their convergence
they carry the eye to a spot near the centre, and so make the boat,
although not very large nor conspicuous, the one and principal
object (see diagram fig. 12).
[Illustration: Fig. 11.]
[Illustration: Fig. 12.]
For the sake of training one's perceptions look at any good
pictures, and in your mind resolve them into line diagrams and see
how these lines fall, and in considering any landscape or other
subject to be photographed make up your mind as to what lines are
suggested, and then select your point of view so that these lines
balance or are symmetrical in arrangement, and also that they
converge towards some point well within the picture, and near the
centre of it.
[Illustration: Fig. 13.]
But in fig. 13 we have a subject in part well composed, but the
composition is spoilt because of the line formed by the road and
fence, which seem to cut the picture in two, whereas could we have
chosen the same subject from a point of view giving such an
arrangement as fig. 14, a difference is at once felt and a more
pleasing effect gained.
[Illustration: Fig. 14.]
[Illustration: Fig. 15.]
[Illustration: Fig. 16.]
Lines which seem to separate us from the picture and cut off one
part from another must be carefully avoided, and an endeavour to
find something which will, as it were, lead the eye into the
picture, should be diligently sought for, and indeed a subject,
however it may interest us, must often be abandoned if it lacks
those things which go to make pleasing composition, remembering as
we should always do that in pictorial work the fact that objects are
curious, or interesting, or pretty, has nothing to do with the case,
but that they are only to be valued according as they act as media
for expressing pleasing ideas, beautiful thoughts and sentiments,
which they will not do if some part creates a feeling of unpleasing
arrangement or design. If a scene does not compose well, we should
as pictorial workers feel no desire to reproduce it. But you may say
"Cannot we often by changing our point of view get an otherwise
ill-composed subject to compose well?" Most decidedly, that is
precisely what we should do, but it is no longer the same subject or
view.
And now let me say that it is often surprising how much alteration
may be made by changing our position. Figs. 15 and 16 are together
an instance of this, the outline here given being made from a pencil
sketch made on the spot, whilst figs. 17 and 18 are examples of the
desirable change brought about by watching and waiting for a change
in the position of light and the condition of the river's tide.
[Illustration: Fig. 17.]
[Illustration: Fig. 18.]
Where the beginner most often fails is in taking things as they are
without pausing to consider whether they might not be improved, and
if so in what way, and then patiently searching to see if such
better way can be found.
Pictorial success will as often as not depend on the exercise of
fastidious taste, which is satisfied with nothing but the very best,
and not quite content even then.
A great deal more might usefully be said with reference to the
composition of lines if space would permit, but this general
reference may be given as a sort of summing up.
If the disposition of the lines constitutes such a perfectly
symmetrical design that it is at once recognised as symmetrical,
then it is wrong, because the artifice by which pleasing composition
is attained is betrayed, and we feel the thing to be artificial. If,
on the other hand, the lines fall so as to make the beholder
conscious of their presence, as, for instance, cutting off a portion
of the subject or presenting a one-sided appearance, again it is
wrong. _In neither case should the lines or the objects suggesting
them be felt at all until sought for, neither as being very right or
very wrong._
In art it is a maxim that the means by which the thing is done
should not proclaim itself, and hence it must apply to pictorial
photography, which is an effort after the artistic. A composition
should please without our quite knowing why, and without our being
able to see the machinery, as it were, by which our pleasurable
sensations are set in motion.
But whilst it is convenient to speak of _lines_ in the landscape, it
is only a manner of speaking, for, as we know very well,
photography, unlike pen drawing, has to do with "tones," that is,
_masses_ of light and shade. Now the general rules suggested as
regards the arrangement of lines, apply in much the same way if we
regard a picture (as we should do) as consisting of masses of light
and shade.
If when standing before a picture we close the eyes and then
suddenly open them, our attention is certain to be drawn to the
highest light or the deepest shadow, and hence, as a general rule,
whichever of these is the strongest to attract attention, that
should be in or near the principal object (indeed it will make of
itself the principal object), and should therefore be well removed
from the margins of the picture.
Refer back to fig. 8, in which the light patch of sky, the light in
the water and the two clusters of light rushes, all form competing
points of attraction, and if these are too near the margins, they
remind us of those margins, hence the improvement in effect when
these are cut away or left out.
But disposing of the highest light and deepest dark does not finish
the matter. There is a certain relative degree of lightness and
darkness between everything in nature. Moreover, colours have to be
interpreted by certain degrees of light and shade according to the
distance objects are away from us, and according to the amount of
light falling on them.
Such relative lightness and darkness is called "_tone_." The word
used in this sense has nothing to do with "tone" as applied to the
colour of a print, which colour we change by a process we call
"toning," and upon the correct rendering of relative tones so much
of the effect of a picture depends, and so much of its emotional
qualities.
Generally speaking, although there are often exceptions, the further
an object is from us the grayer it seems. White becomes less white,
and dark objects grow less dark, until in the distance both, under
ordinary circumstances, come almost to the same "tone," and we see
the distance only as a gray hazy mass.
If for a subject we have a figure of a woman by a stream of water
and we make an under-exposed negative of it, or develop the negative
to too great a density, we shall very likely have a print in which
the water and the woman's apron and cap come very much whiter with
regard to the rest of the subject than ever they appear in nature,
whilst the distance will very likely come too dark. Here we show a
disregard for the correct rendering of relative tones and the effect
is hard and harsh, unlike nature. We must therefore endeavour, both
in exposure and development and printing, to preserve relative tones
exactly as they are in nature, and constant study and observation of
nature should be carried on in order that the eye may be trained to
know how things come relatively in nature, and so be able to decide
at a glance if the photograph is good.
Ultimate success, by the way, often depends less on knowing what to
take and how to take it than on a well-trained judgment which knows
what is good or bad when we have taken it.
Whilst the mere lines or forms of objects may impart some amount of
feeling and sentiment to a scene, inasmuch as there is restfulness
and repose in the long horizontal lines of the river-side pastures,
something rhythmical in the sinuous curves of the winding stream, or
vigour and variety in the irregular forms of the rugged cliffs and
so on, yet the ideas and feelings which the picture will promote
depend more on the lights and shades, and the masses contrasting or
merging each with each.
But Nature does not always present herself in pleasingly arranged
masses, and is consequently at such times commonplace and
unpicturesque in the literal sense of the word. At such times she
will not attract the pictorial worker any more than she will when
perchance the lines and groupings are unsuitable.
The landscape which basks under the full blaze of sun, glittering
throughout every inch with a myriad twinkling lights and sharp
details, awakens no feeling akin to those which probably everyone
feels when in the twilight of evening plane after plane recedes as
one broad flat tint behind the other. Under the bright light of day
we may wonder at the richness and plenty upon the earth, we may
rejoice in that there are so many curious and pretty things to look
at, but these are like the feelings inspired by reading a book on
natural history, rather than the emotions created by the perusal of
a poem, or listening to sweet music.
[Illustration: Fig. 19.]
Compare for a moment the two photographs, fig. 19 and fig. 20.
The first is by no means an extreme case of the ordinary photograph,
and notice that although the composition is fairly good as far as
grouping goes, there is an absence of any quality which might make
one feel anything outside the bare recognition of the facts
depicted, but the second, if it be good at all, must depend for
admiration on a certain amount of sentiment which it suggests or
creates. You will notice that in the first there is no sense of
distance, and although a church tower, behind the masts of the
boats, is half a mile or so away it does not possess the "tone" and
veiling of atmosphere which would make it appear distant. Every part
of the view seems equally near, or nearly so; the eye wanders over
the whole, alighting on details here and there which interest and
amuse, yet there is an absence of just that breadth which is
noticeably present in the second example.
[Illustration: Fig. 20.]
Now let it be distinctly understood that detail, its omission or
suppression, and its introduction or sharp delineation, is not a
question of lens focus only, or even chiefly, but it is largely a
question of light. Imagine the photograph, fig. 19, with the greater
part of the detail taken out so that the quay, the houses, the
shore, etc. were just broad masses of lighter or darker tone, should
we not then get a composition which would be less disturbing, more
compact, more concentrated in interest? Is not this the case in fig.
20, in which detail is almost entirely absent? And yet detail could
not have been truthfully introduced in this photograph, because with
the light in the position it is, and in the misty evening air, _no
detail was there to reproduce_; it was the fact that objects ranged
themselves in masses one against the other, leaving room for
imagination and creating ideas that determined its selection and its
consequent portrayal.
In many cases a clear and sharp delineation of details will perhaps
be desirable, not, however, for the sake of showing detail, but just
so far as the production of the effect may require; on the other
hand, just the full amount of detail that a lens will give is by no
means always wanted.
_Lenses were not invented for pictorial purposes_, and therefore
there is no reason for concluding that what the lens gives is
necessarily right, for remember that we started with the distinct
understanding that we were merely _applying_ to a certain purpose
just so much of the photographic process as we considered we needed;
because I have the means of travelling at sixty miles an hour there
is no reason why I should not apply the same means of locomotion to
coaching a pedestrian at a tenth of that speed if I choose. It may
be said that in the two photographs referred to the comparison is
not a fair one, because so much depends on the sky. Granted that
much in the second example does depend on the sky, which is an
essential part of the picture, and indeed one cause of its very
existence, but in the other (fig. 19) the presence of clouds would
not improve the pictorial faults to which reference has been made.
As a mere record or portrayal of Old Woodbridge Quay, the absence
of clouds is as much a characteristic of its particular species, as
the clouds in the second one are inseparable from its existence.
So, but little more than half hinting at the principles involved in
the due suppression of unnecessary details, and the elimination of
undesirable objects in order to obtain breadth, and having said but
little as to the preservation of correct relative values or tones, I
must pass on.
Every corner of nature's broad expanse is, as it were, enveloped in
atmosphere, and invisible as we are commonly in the habit of
considering it to be, it affects to a greater or less degree
everything we see, and the visible atmosphere is often responsible
for some of nature's most beautiful and most appealing aspects.
Obviously then we cannot afford to leave out so important a
contributory to picturesque effect, and it is on this account rather
than on account of sharp or un-sharp detail that the question of
stops and lens apertures comes in.
Look at the image of a landscape on a moderately hazy day, as it
appears on the ground-glass focussing screen of your camera, using
the lens at full aperture--then quickly insert _f_/32, and notice
the difference. Not alone have objects near at hand and more remote
become more sharply or more equally defined, but you may also notice
that objects are _more brilliant_, and that a sense of atmosphere
has been cut out.
Compare if you will two photographs, the one made respectively with
full aperture of _f_/6 or _f_/8 and the other made with _f_/32 or
_f_/45, and provided that in the first case we have not actual
blurring to the extent of destroying form and structure, does not
the first remind you more of nature? I do not say it is so
instructive, so surprising, so dainty, or of such exquisite finish,
but is it not more reminiscent of the _effects_ we remember to have
seen and _felt_ in nature. It is not the function of this article to
say to what optical laws this difference is due, and yet the student
may expect to receive something by way of practical working
instructions.
My recommendation is then to use a single landscape lens or the
single combination of a doublet, and in starting to use the full
aperture.
With this it may be that when the foreground is moderately sharp,
trees more remote are so ill defined as to appear as a collection of
little blots and irregular patches. Whilst sharp detail in all
places may not be productive of pictorial effect, yet the extreme
opposite will be displeasing in another way, and it will be best to
secure just _so much definition and no more_ as shall save the
representation from appearing to have been wilfully put out of
focus--once let the destruction of detail be obvious and we betray
the artifice by which we are working, which is just what we should
avoid.
In the case just supposed then, we may now introduce the first stop,
simultaneously racking the lens in a little until we get middle
distance without unpleasantly obvious blurring. The foreground may
be a little out of focus, and in practice I find it is rather
helpful to general effect if detail is sacrificed more in the
foreground than in the middle distance.
This I believe is contrary to the teaching of many, but my feeling
is that with a sharply defined foreground the eye is attracted and
the interest so far arrested, that it is difficult to travel further
and enter into the poetry and sentiment of the scene beyond.
Wide-angle lenses have a double disadvantage, shared in part by
so-called rapid rectilinear doublet lenses. In the first place they
flatten the view, bringing distant planes to appear as near as the
nearer ones, and by including a comparatively wide angle they bring
into the plane of the foreground, objects so near that they appear
out of proportion, and hence proportions are false when judged as
the observer must judge by the standard of visual perspective.
A long-focus, narrow-angle lens necessitates a camera which racks
out to a considerable length, and probably a greater extension than
any camera in the ordinary way can give, would be an advantage on
some occasions.
Passing reference has been made to the interpretation of colours in
nature in their true relative value of black and white.
If we have a subject in which brilliant orange-coloured rushes in
autumn are seen as glowing bright against a background of dark blue
water, and the rushes made still more golden of hue by the ruddy
rays of a sinking sun, a difficult case is before us.
Such a case I remember very well in the south of Devonshire, close
to what is known as Slapton Ley. It was late afternoon in November,
and from over the rounded hills behind me to the westward, the
declining sun sent warm red rays on to the belt of faded reeds which
stretched out into the expanse of the still land-locked water of the
Ley--a great sheet of fresh water which placidly lay under the
shelter of the bank of shingle which alone separated it from the
ever-restless sea--placidly listening to the ceaseless voices of sea
music, and at this particular hour reflecting the sky deep blue and
of almost leaden hue--just above the bank rose the full moon, orange
in tint, on a background of blue-green sky--the yellow reeds,
kindled into glowing amber tints by the sun's rays, flamed out from
the deep blue water--yellow the shingle bank against the blue water
and green-blue sky, deeper yellow the moon as it rose from out the
sea. So grand a scheme of colour that by its side the essays of the
most daring painter might well seem feeble, so exquisite a poem that
the intrusion of the photographer, analysing the values and tones
and calculating his powers of reproduction seemed like sacrilege. In
the main it was yellow, orange-yellow, and red standing out as
luminous against the deep blue of water and only a little less blue
sky. It was gorgeous non-actinic colour appearing as _light_ against
a highly actinic but _darker_ colour. The consequence of an
indiscreet exposure with an ordinary plate might be anticipated to
produce _dark_ rushes against a _pale grey_ background of water, and
so probably the very effect we were minded to secure, reversed and
dissipated.
This is an extreme case, perhaps, but throughout the whole range of
nature the contrasting and blending of adjacent colours is so subtle
a thing that I should feel one were throwing away at least a
possible advantage by not using colour-corrected or isochromatic
plates on nearly every occasion, and in order to get the full
advantage of isochromatic plates, I should consider the addition of
a yellow screen an essential.
The rapidity of one's plates, isochromatic or otherwise, must be
governed entirely by the nature of the subject, as also to some
degree must be development and subsequent printing.
In every case I would endeavour to get a comparatively thin
negative, with even the portions representing deepest shadows
slightly veiled. "Clear glass shadows" is an enormity and an outrage
both of science and art; equally are solid high-lights to be
shunned. With modern printing methods it needs much less than actual
opacity in the negative to produce white paper, and if the picture
requires any part of it at all to appear as quite white, no subject
will need more than the very smallest region to be so. A general
softness and very subtle gradation, with a total absence of
"sparkle" and brilliancy in the negative, will yield by at least
most processes the most suggestive print, bearing in mind that
delicate gradations suggest atmosphere, and atmosphere is one of
nature's most precious qualities.
Whilst plain salted papers sensitized with silver present
possibilities not yet sufficiently exploited, yet until such time
that something more entirely satisfactory in all respects is given
us in silver papers, platinotype and carbon, and perhaps also gum
bichromate will be the processes most suitable for our purpose.
Personally, platinotype has been the favoured medium, being, as I
believe, more ductile and more amenable to various methods of
control than is generally recognised.
And leaving much more of importance unsaid than space limits admit
of my saying, I must leave it.
_A. Horsley Hinton._
_Architectural Photography._
[Illustration]
To the majority amateurs, the photographing of architectural
subjects presents considerable, and in many cases apparently
insurmountable difficulties. Undoubtedly there are difficulties to
be grappled with, but they are neither so formidable nor so
numerous, but that any ordinary photographer with the average amount
of common sense can master them be he so minded.
Unfortunately there are a great many who take up photography as an
amusement to whom the slightest departure from the ordinary routine
presents a difficulty. It is however to the amateur photographer who
desires to be able to portray architecture, be it either of our
cathedrals, churches, historic mansions, or places of personal
interest, and at the same time wishes to be able to do the subjects
fair justice, that it is hoped the following particulars may be of
some service.
To the beginner taking up this or indeed any branch of photography,
size is of course a great consideration either from the weight
carrying or pecuniary point of view. Another reason is the fact that
young photographic workers have an idea that the smaller the plate,
the easier the working. Sound though this reasoning may appear,
nevertheless it is not entirely correct.
As a matter of fact all things being taken into consideration the
larger the plate up to 12 × 10 or 15 × 12 employed the more rapidly
will the worker progress.
Large plates, especially in architectural work, tend to make the
operator more careful and conscientious when out with the camera;
and even more so when in the developing room. So much more can be
done with a large plate than with a small one; the use of a large
plate moreover checks the common failing so prevalent among amateurs
of rushing work and recklessly using plates.
Taking all things into consideration, I would strongly recommend the
whole plate or 10 × 8 camera to the student taking up this branch of
our art.
In selecting a camera purchase a front extending one with bellows
only slightly tapering. See that it has both rising and cross
movement to the front, and also that the amount of movement in each
case is a not too restricted one. Makers, unfortunately, do not give
sufficient attention to this matter, the usual rise allowed being
very slight whereas it should be at least equal to one-third of the
longest way of the plate; even more than this is advantageous if it
can be obtained. By the rise I mean the amount of upward movement
that can be obtained, the lens being in the centre before starting.
The cross-front should have a movement of about one-quarter of the
length of the plate each way.
It may be useful to know that a little more rise can be obtained by
the placing of the lens above the centre of the cross-front;
reference to the photograph of camera will explain this matter more
fully.
The swing-back should be a practical one, working from the centre,
and capable of being swung either to or from the lens.
In many of the cheaper front extension cameras it is not possible to
use the swing-back when tilting the camera down, only when tilting
upwards. The swing-front, although not an absolute necessity, is
undoubtedly a movement possessing great advantages, especially when
the front is raised rather high, and one is using a lens of limited
covering power. This movement should be acquired if possible.
The camera should possess double extension, focussing by rackwork,
and having a reversing back so made that it will fit on all ways; it
is then possible to draw the slide shutter out in any position.
In selecting a tripod stand purchase one of the kind known as the
sliding leg variety, two-fold is better than three, giving greater
sliding power. The top of stand should be as large as possible; this
is preferable to a turntable, as this piece of workmanship is seldom
rigid after a little use, and some difficulty is experienced when
trying to spread the legs out rather wide. A two-fold Ashford stand
is as good as any on the market.
The blocks herewith illustrate the kind of camera used by myself,
and with the exception of the turntable, which is not a great
success, it answers all requirements.
In the selecting of suitable lenses a great deal will depend upon
the inclination of the purchaser and the depth of his pocket.
There is such a great variety upon the market at the present time,
that to the young photographer the buying of the right lenses is
somewhat a difficult problem.
[Illustration]
[Illustration]
The Zeiss series are undoubtedly the finest obtainable and for
architectural work are unrivalled, possessing great covering power,
good marginal definition, and in fact very fine definition all over
the plate. The lenses of this series, although quite new, have met
with great favour amongst architectural workers.
They work at an aperture of _f_/18, but I understand that they can
be opened to _f_/16 and numbered on the _f_ system. As regards their
relative working capabilities they give about the same picture at
_f_/32 that the majority of wide-angle lenses give at _f_/64.
The Goerz anastigmats are also another very fine series but do not
give anything like the covering power of the last mentioned, and
moreover are nearly double the price. Their special merit is that
one can work at _f_/8 or _f_/11, and get a picture sharp up to the
edges. Taylor, Taylor & Hobson also make a good wide-angle lens,
possessing great covering power and at a moderately low price. With
one of their nine inch lenses I have covered a plate 12 × 10 inches.
[Illustration: "GATHER THE ROSES WHILE YE MAY, OLD TIME IS STILL
A-FLYING." ALEX. KEIGHLEY.]
For a whole-plate camera, a useful battery would be a 5 inches,
7-1/2 inches, 9 inches and 12 inches; for 10 × 8, 7 inches, 9
inches, 10-1/2 inches and 14 inches. The three last in each case are
the most useful.
Having selected the lenses, another very important point and one not
to be decided hastily is the question of levels. Four are required,
two circular and two ordinary. They are placed as follows: Fix the
circular levels, one on the baseboard near the front of the camera,
the other on the top of the back part of camera. The other two
should be placed one on the side of the back part and the other on
the back of camera just under the reversing back. Care must be taken
to purchase slow moving levels as some work so quickly that it is
next to impossible to level the camera with them, and as this is one
of the most important points in the whole business, too much care
cannot be taken in selecting and fixing the right kind of level.
[Illustration]
The focussing screen should be ruled as accompanying diagram. This
will divide the screen into inch squares, working from the centre,
and will considerably assist the photographer in "sizing his subject
up."
One other thing required is a set of clamps for binding the tripod
legs together. These are, I believe, made by George Mason, of
Glasgow, but any dealer will procure them for you.
The use of the right kind of plate constitutes a very important
factor in the production of a satisfactory negative, particularly in
this branch.
Owing to the greater difficulty experienced in developing extra
rapid plates, one generally sees the slower variety recommended. No
hard and fast rule can however be laid down. To gain the best
result, the plate must be suited to the subject.
For instance, in a very dark interior in which heavy black shadows
predominate, many of them appearing much darker than they really are
owing to their close proximity to a strong light, the quicker the
plate used the better. This tends to break down the harsh contrasts,
and at the same time the shadow detail is considerably better
rendered.
On the other hand, working in a light interior or one which is flat
owing possibly to the large amount of light present, a slower plate
can be used with advantage, and, providing the exposure is
sufficient the result will be all that is wished for.
Exteriors, particularly those in sunshine, should be photographed on
a fairly quick plate. Slow plates, although good, do not yield
nearly such good negatives, and unless very fully exposed give
excessive hardness.
Taking this class of work all round, the quick plate is the more
useful of the two and is undoubtedly the best for interior work,
particularly such interiors as one meets in our English cathedrals.
For all subjects possessing strong high-lights, such as windows,
stained or otherwise, rapid plates combined with a suitable backing
composition yield the best results, and I would impress upon the
reader the fact that no plate should ever be placed in a dark slide
without being covered at the back with a suitable composition for
the prevention of halation.
[Illustration]
The value of this agent is distinctly demonstrated by the
accompanying illustrations, and I would point out the fact that the
negatives were both developed with the utmost care. The unbacked
plate was so developed as to prevent the appearance of halation as
much as possible, and it will be noticed that all portions of the
photograph, other than that where halation has occurred, are nearly
as good in the unbacked as in the backed one.
Having obtained all the apparatus and materials, a very good subject
to begin on and one giving good opportunities for the exercise of
the various movements connected with the camera, etc., is a general
view of the choir in some cathedral or church near at hand.
Having erected the camera, the next thing is to decide upon the most
pleasing point of view.
Speaking from my own experience I would advise the shifting of the
camera either to the right or left, so that the centre aisle is
thrown slightly in perspective. This tends to give a much better and
decidedly more pleasing effect to the resulting photograph. Of the
two sides, moving to the right seems to be the best. The next item
is the fixing of your ground line, this must be so arranged that it
is quite clear, not obstructed by the backs of chairs, etc., which
look very badly if left standing. Personally, I have generally found
it necessary to move one or two rows of chairs so as to make the
ground line myself.
In adjusting the height of the camera from the ground it is well
never to exceed six feet. Five feet to five feet six inches is the
most useful height. This will give a photograph in which the point
of sight is the same as that of the person actually viewing the
subject.
The placing of the camera on step ladders, chairs, or other
supports, so as to overlook objects in the immediate foreground is a
practice to be condemned, giving results very rarely pleasing and
always bad from the sightseer's point of view.
Having settled upon the point of view and the lens to be used, the
student should then roughly focus the image. Notice the amount of
subject on the plate and how much rise is required.
If having a camera such as described, the rise is easily
accomplished and the camera can then be truly levelled up. Care
should be taken over this as unless you have the camera exactly
level you cannot expect a true picture. The bubbles of the levels
should be _exactly_ in the centre, _a little bit out will not do_.
[Illustration]
If it is found that the rising front fails to give the amount of
subject required, recourse must be made to the swings, and it is
here that the swing front triumphs over the swing back.
To swing the back necessitates the shifting of the camera and tripod
stand, and at once throws all the levels out of gear. Then comes
re-focussing, etc. Sometimes this will have to be gone through five
or six times before the desired amount of swing has been achieved.
Owing to the re-focussing required every time the camera is moved it
is very difficult, especially for the beginner, to rightly estimate
the amount of rise required.
With the swing front the desired amount of rise is attained easily
and quickly, and it can be worked with the head still under the
focussing cloth, which is a great convenience. At the same time the
baseboard and back of camera always remain level.
After gaining the correct amount of rise the sides of the subject
should be considered. A golden rule to remember in this class of
work is when you show a column, show the base of it, and always
start the sides of plate with either half or three-quarters of a
column. It looks very queer to see the bend of an arch wandering
away out of the side of the picture without any apparent support. In
arranging the sides it is usual to have a preponderance of subject
on the opposite side to which the camera is, and to start that side
with a column. Sometimes the subject fails to fit the plate nicely,
in that case it is better to trim the print than to have
uninteresting features present.
Of course a great deal depends upon the personal taste of the
worker, what one man considers right another will rebel against; so
although I advocate the use of columns to fill the sides of the
plate it does not follow that that is the one and only method of
photographing these subjects.
The student having carefully gone into these matters and arranged
the subjects to suit his own satisfaction the question of what point
to focus for arises, and indeed in very dark interiors the question
of focussing anything at all comes in. A method I use myself is to
roughly divide the distance from the camera to the farthest object
in half, and then to focus midway between the camera and the middle
of the subject. Then stop down the lens until the most distant
object is sharp. In practice I have found this rule so good that I
can recommend its adoption for all subjects, and if carried out
correctly will always result in the production of crisp negatives.
Exposure is not a very difficult thing to overcome. Arrange the
focussing cloth well over the head, open the lens out to its largest
aperture and remain under the cloth until you can see the image
distinctly all over the plate. Then without uncovering the head
proceed to slowly stop down until you can only just see the image
all over the plate. Now using a plate of the rapidity of Barnet
extra rapid, an exposure of ten minutes will yield a satisfactory
fully exposed negative.
The varying exposures for other plates and stops are easily
obtained. For instance you find the image can just be seen all over
at _f_/32 and you wish to use _f_/64 The exposure will be forty
minutes.
After having used this method for over seven years, and having
invariably found it correct, I can unhesitatingly recommend its
adoption, and if used with a little common sense the worker will
seldom suffer from his plates being either badly under or
over-exposed.
In photographing side aisles, transepts, or long rows of pillars,
the worker is often troubled by the unnatural way in which the floor
runs up. This is more especially noticeable when there are no
prominent objects in the immediate foreground. A considerable amount
of this can however be overcome by the lowering of the camera to
about three feet from the ground. It is here where the sliding legs
of the tripod stand become of service.
I would ask the student always to use the longest focus lens
possible, consistent with the effect desired.
The use of extreme wide-angle lenses has had a disastrous effect
upon the public taste in respect to architectural photography due
principally to the abortions one sees exposed for sale in the shop
windows of our cathedral cities.
It should be seldom necessary for the amateur to use very wide-angle
lenses. Of course, when it is a question of getting a detailed
photograph in a confined situation a wide-angle lens is of great
service. But it is when you see the whole length of a cathedral
photographed on a whole plate with a five inch lens that the fault
is so noticeable.
In photographing exteriors great care should be taken in the placing
of the camera in a suitable spot. Try and so arrange it that the
short side of the building does not run off too violently, indeed,
it is often much better to leave out a portion of the subject rather
than to cram the whole subject upon the plate.
General views are much better if photographed when there is a little
sunlight. This gives to the subject a sharp, clean-cut appearance.
Details on the other hand are better if photographed in a subdued
light and slightly over-exposed.
In focussing very high subjects some difficulty will be found in
getting bottom and top in focus at the same time, especially if the
lens be strained by either altering the back or front of the camera.
The best place to focus is a little way above the centre of the
screen, so that when stopped down the bottom of the building is
quite sharp. A slight softness towards the top of the subject is
scarcely noticeable in the final print.
The exposure of exteriors varies between three seconds at _f_/64 to
ten minutes, and no correct guide can possibly be given. To the
beginner a Watkins' exposure meter will here be of some service.
If people are continually passing and repassing stop the lens down
to _f_/64 and give as long an exposure as is possible; this will as
a rule completely obliterate them. I have found that an exposure of
from ten to twenty seconds entirely destroys all trace of moving
objects.
Another method of making an exposure where there is much traffic
past the building, and perhaps people standing about whom you cannot
very well ask to move, is, to break the exposure as many times as
possible. Expose for two seconds, then wait until the traffic has
somewhat altered; then give another two seconds and so on until
finished. By this means I have been able to photograph buildings in
the centre of a crowded street or thoroughfare without a trace of
anybody showing.
It is often interesting for the student to be able to successfully
tackle the photographing of drawing-room, ball-room, or other
apartments either of his own or friends' houses.
This work is considerably more difficult than it seems; and it is in
such subjects that the taste of the operator becomes manifest. A
great deal depends upon the point of view chosen and also upon the
arrangement of the furniture.
If a long room, the camera should be placed at one end at about a
quarter of the width of room away from one side and from the end
wall. Keep the camera parallel with the sides of the room and use
the sliding front so as to obtain more of the opposite side of the
room. This will give the ceiling a true square appearance and the
side of the ceiling will not run off with an unpleasing effect.
In some subjects it is perhaps necessary to include one or more
windows. This can of course be accomplished by the aid of backed
plates, but it is always better to block those particular windows
out. This is usually done by covering the outside with black cloth
or brown paper or pulling the sun blinds down. To get the effect of
the windows you must remove the paper or cloth at the end of the
exposure for a few minutes, three minutes being generally
sufficient. By this means it is possible to show the landscape as
seen from the window. Do not place your camera too high. Four feet
to four feet six inches is quite sufficient. If the camera is higher
you look over the immediate foreground objects, touching the ground
past them, which is undesirable.
In arranging the furniture be careful that round or oval objects are
not placed so that they appear on the edges of the plate which gives
them an exaggerated appearance.
In exposing on all such interiors I would strongly recommend a very
full exposure, the object being to flatten the subject. A great
thing to study in this branch of work is the careful lighting of
your subject. This can be largely varied by the use of the inside
blinds, also by the sun blinds found outside many windows. It is
_not_ advisable to draw the blinds up to their fullest extent. By so
doing you accentuate your cast shadows thrown by tables, chairs,
etc. In fact, the softer the light in the room coupled with a
corresponding exposure, the better the result. Another point to
notice is that a comparatively dull day is often the best for
interior work, the light being much softer and subdued. As a slight
guide to exposure I would suggest that an additional twenty-five per
cent. be added to that recommended for church work.
_John H. Avery._
_The Hand Camera and its use._
[Illustration]
What is the best form of hand camera? How often this question is
asked, and yet how impossible to give any definite reply, the
conditions of use, and requirements of each worker being so widely
different. One, desires a form of apparatus, capable of being closed
up into the smallest space, weighing but the least possible number
of ounces, the necessary movements, confined to touching a spring,
or pressing a button, and the total cost not to exceed two or three
pounds, while others do not care so much as to its possessing these
qualities, if by a little increase in bulk, weight, and cost, it is
capable of use in a less restricted manner, on subjects of wide
variety, and under such conditions of light, and atmospheric
effects, as, when shutter exposures are being given, call for the
_maximum light passage_ to the plate.
Assuming the camera to be intended exclusively for use without a
tripod, then it becomes not a difficult matter to point out its
essential features. First and foremost, it should be characterized
by simplicity in construction, and every part be easily accessible,
complicated movements being rarely found necessary, except perhaps,
to raise the price of the instrument. When being employed in the
field, the camera and its working parts ought not to need the
slightest consideration, each movement, whether they be few, or
many, being made, without requiring troublesome attention at the
moment when every thought should be devoted to the subject.
The component parts of an instrument, complete and effective for
this class of work, may be taken to be a good lens capable of
covering at _f_/8, a shutter, some simple means of focussing,
adequate finders, and the means of carrying plates either in some
form of magazine, or ordinary dark slides.
Each system of holder for plates possesses its own distinctive
advantages, which are preferable, depending entirely on individual
needs, or tastes. Some admire one method, and some the other.
When plates are carried in one of the many forms of magazine which
cameras are nowadays fitted with, it is _important when re-charging
it_, that care be taken to see _each sheath and plate is laid true_
in its place, as the slightest irregularity at this point, means
certain trouble when changing a plate after exposure, indeed,
perhaps fifty per cent. of the misfortunes which occur when out at
work, from failure to act of the changing arrangements, _are
directly caused by carelessness when laying the plates in the
magazine_. Given reasonable care in this matter, almost any of the
modern automatic changing methods, may be relied on to answer
satisfactorily. When however the slight additional bulk, weight, and
it may be increase of cost is not objected to, then there can be no
denying separate dark slides possess many and important advantages.
No need to fear a wasted day, caused by some plate sticking, and
rendering further work impossible, without having recourse to a
dark-room, which probably is miles away; and again, one must not
overlook the opportunity they give of carrying plates of different
degrees of sensitiveness, a matter of service, when subjects to be
dealt with are varied, such as, say, clouds and water, landscapes
and figures. In the first case, when light is fairly good, the
ordinary speed plate will be found amply quick enough during the
daytime, and fifty per cent cheaper in price. When open landscapes
are being taken, during summer time, medium rapid plates generally
will be quick enough, but many opportunities, for pictorial work,
arise under conditions of atmosphere and light, in which to obtain
fully exposed negatives with a shutter, demands a plate of extreme
sensitiveness, and if for no other reason than that they offer this
opportunity of carrying a varied assortment of plates, many workers
prefer dark slides, to any form of magazine.
There are advantages, and disadvantages, with both systems, and it
becomes simply a question for each worker to consider which fulfills
his requirements best.
_The Lens._--Good work can be, and is done, with cheap single
lenses, but the opportunities offered are considerably restricted,
what is needed, being such a lens as may be used at full aperture of
_f_/8 or _f_/6, and will then cover the plate from corner to corner,
sharply. This is necessary not only because the actinic quality of
light is not always over good, but that moving subjects demand the
shutter should be working with rapidity, sometimes indeed with
considerable speed: under which conditions two factors are
absolutely essential, a large working lens aperture, and a rapid
plate. It is well, therefore, to _buy the best lens you can afford_,
it more than pays in every way. For 1/4-plate work, a _rectilinear_
of 5, or 5-1/2 in. focus, working say at _f_/5.6, and with iris
diaphragm, by one of the best makers, will allow work being done
under any condition of weather, or other circumstances, when shutter
work is possible.
_Finders._--Years ago, the question of whether finders were
necessary, or not, in a camera of this kind, was a matter on which
some at least expressed very different opinions, from those now held
by most workers. Further experience has shown that when certainty in
working is desired, some kind of finder is an absolute necessity as
part of the working mechanism. It usually takes the form of a small
camera obscura, what is required being, that it should not be too
small, should give a perfectly discernible image, and be so
adjusted, that only so much of it is shown, as will be projected on
to the sensitive plate, when the exposure is made. The reason of its
importance is that it _enables the subject being arranged_
tastefully, as well as ensuring that the whole of it is on the
plate.
Where no attempt at pictorial work is intended, and the important
matter is simply that the object being photographed should be in the
_centre of the plate_, then it is only necessary that the finder
should show as wide an angle of vision, or a little wider than the
lens being employed inside the camera. But when something more is
aimed at, _viz._: _Tasteful composition over the whole plate_, then
it is necessary to block out on the finder all excess of view,
beyond what will be received on the sensitive plate.
_The Shutter._--What particular form may be best is a matter of
doubt, but whatever it be, exposure must be possible without
vibration, it should give greater exposure to the foreground than
the sky, and ought to allow of being regulated for exposures ranging
from 1/4th of a second up to perhaps 1/100th for ordinary work.
Where shutter work has to be done, which demands anything less than
1/100th of a second, then special shutters for the purpose are
needed, but after having used hand cameras of one form or another
for the last nine or ten years on such classes of subjects as are
ordinarily dealt with, the occasions on which any greater speed than
1/30th of a second has been called for have been extremely rare. It
may be said this would not allow of taking subjects such as a close
finish of a cycle race and such like, which is quite true; did
occasion arise for so doing, then a shutter such as the focal plane
would be employed as a matter of course. But by far the greater
amount of work done with hand cameras would be the better for
receiving a longer exposure, better because light action on the
sensitive plate would be more thorough, and far better because when
slowly moving objects, such as waves rolling shoreward, are given
1/10th instead of 1/100th of a second, we get less of "_petrified
naturo_," and a more natural appearance in the resulting
photographs. As a general rule it is well to give the _slowest
exposure possible_.
_The Focussing Arrangements._--These need be only very simple, and
generally are done by scale to distances. As a rule with the lens
working at _f_/11, and the scale set at 15 feet, it will be found
that the depth of focus is sufficient for most ordinary work, and
any alteration in the focussing seldom necessary, when dealing with
subjects where figures are included, that are not required to be
approached much closer than the distance mentioned.
So far as may be necessary for _hand-camera work_ simply, the
instrument should be without complications, is better for having a
_good rectilinear lens_, needs a shutter easily adjusted for
exposures ranging if possible, from a 1/4th of a second, up to say
1/100th, properly adjusted finders, some means of quickly altering
the focus of lens, one or other method of carrying the plates or
films, and for _purely hand-camera_ work, there is _no need_ for any
other addition to it.
Passing away from the camera to its use, one is faced immediately
with the fact, that in spite of the multitude of such instruments
now in use, the _general average of results_ produced by its means
are, in quality, unmistakably below those done with a camera and
tripod, nor is the reason for this far to seek. In the latter case,
a plate of medium rapidity is generally employed, such an exposure
given, as makes no serious _strain_ on the developer used to bring
the latent image fully out; the action of light having been ample,
and the plate not so easily spoiled, as one of higher sensitiveness,
there is not that call for such skilful treatment, as where light
action on a highly delicate emulsion, has been but brief, and needs
to receive careful handling, before good, well-graded negatives may
be produced.
To use a hand camera is the simplest matter imaginable, to properly
employ it the most difficult--simple, because of the facility with
which plates may be exposed, difficult, because to succeed, demands
careful practice, and a thorough understanding of photographic
manipulation. We must have _learnt to see_, and that quickly, must
have gained coolness and self-restraint, and perhaps not the _least
qualification necessary is that of being a good photographer_.
Whether content to produce good straightforward representations of
such scenes as come before you, or more ambitious attempts at
pictorial work be made, they can both be done with the hand camera
quite as well, nay indeed, given sufficient technical skill, and
trained perception to see the beauty presented in line and mass,
it is by no means clear this form of implement does not offer
greater facilities for successful working, than the more complicated
form used with a tripod.
[Illustration: BIRCH AND BRACKEN. W. THOMAS.]
The choice of subject is only bounded by the limits of exposure,
speed of plate and actinic action of light available. The first has
already been touched upon, when the lens, and shutter, were dealt
with.
Plates have recently been so increased in speed, that it becomes
necessary to somewhat modify advice, which a year or two ago, might
have been perfectly correct, _viz._, to work with the fastest plate
procurable. But there is this advantage now, as then, that if some
convenient form of actinometer be used to test the light, we are
able to judge at once, what speed of plate will be necessary to deal
with each subject as it arises. There are several forms available,
amongst which, the one introduced by Watkins, made so that it
becomes a permanent part of the camera, answers remarkably well,
especially as it cannot be left at home, without being noticed. In
developing shutter-exposed plates, if full exposure has been
obtained, then the ordinary modes of procedure suffice, so also when
over-exposure occurs, but by far the greater proportion of failures
one sees in this class of work, arise simply _from under-exposure_.
There seems so much charm in driving a shutter at its highest speed,
and at the same time using the lens stopped down, to secure sharp
definition, the wonder is, not that failures flourish, but that any
good work is done at all.
With regard to particular developers there is only this to be said.
Whatever agent be employed, so arrange that before density is
obtained, _all the detail you require_ is first brought out; this
simply means, if pyro is being used, it is kept low, until the plate
is ready to be treated for density, then a further addition of pyro
and bromide will generally suffice to rapidly finish off the work.
When a batch of exposed plates is being dealt with, a most certain
method of negative making, will be found in employing in one dish,
either one or other of the following one-solution developers:--
NO. 1 FORMULA.
Amidol 20 grains
Sodium sulphite 1/2 oz.
Water 7 "
NO. 2 FORMULA.
Dissolve in water 20 oz.
Metol 75 grains
then add
Sodium sulphite 1-3/4 oz.
Carbonate of soda (crystals) 1-3/4 "
Bromide of potassium 6 grains
NO. 3 FORMULA.
Sodium sulphite 1-1/4 oz.
Carbonate of potassium 1/2 "
Eikonogen 1/4 "
Boiling water 12 "
Any of the above developers will be found to rapidly bring out all
there is in the plate, and if over-exposure is feared, they may all
with advantage be diluted, with an equal quantity of water, in order
to slow down their action.
In another dish, it is advisable to have the following
_re-developer_, to impart density to the plates, as they become
ready for that operation, or to successfully deal with any, which
are found to have been considerably over-exposed, and upon which,
the first developer is acting too vigorously.
RE-DEVELOPER.
NO. 1.
Hydroquinone 1/4 ounce
Sodium sulphite 2 "
Potassium bromide 1/4 "
Boiling water 12 "
NO. 2.
Washing soda 2 ounces
Sodium sulphite 2 "
Water to make 12 "
For use mix equal quantities.
By employing two different developers in the manner suggested, it
becomes a simple matter to produce good negatives, from plates
having had all kinds of exposures, some under, some over, and it may
be some which have had about the right exposure; in this way one of
the most fruitful causes of failure in the production of hand-camera
pictures, _error in exposure and development_, is minimized, if not
altogether done away with.
There are sometimes occasions when out with a hand camera, when
subjects present themselves, offering exceedingly good opportunities
for securing pleasing little pictures, but which require one, or two
seconds' exposure, to render them successfully. At such times it may
generally be arranged to rest the camera on a stone, wall, or gate,
or to hold it pressed against a tree, or some other rigid support.
As an example, the illustration of a woodside with birch trees,
facing page 136, may be pointed to. In this instance, when out
cycling, the place and lighting on the tree trunks, struck us as
pleasing, and worth trying to secure a record of, even though but a
hand camera was being carried at the time.
Having dismounted, and found a point from where it might be
attempted, and where conveniently grew a single tree, the lens was
opened to (if recollection does not deceive) _f_/11. Then the camera
jammed close to the tree trunk, and two seconds' exposure given,
taking especial care that no movement took place.
The plate being in due time carefully developed, and as far as
possible contrasts kept down, the result proved satisfactory
enough.
It could more conveniently have been photographed, of course, if a
camera and tripod had been available, but it is one of many such
instances, where, when shutter exposures only had been prepared for,
occasions arose, demanding longer exposures than were possible,
unless, some such temporary support be pressed into use, as in this
instance.
For successful work, see that the camera is simple, its parts, of
the best your pocket can afford. Give the slowest exposures your
subject will allow. Develop for softly modelled negatives first,
getting what density is required afterwards. See that the camera is
held perfectly steady, during exposure, and don't forget it is
simply a camera, and lens, and will require _you behind it_, just
the same as any other employed with a tripod, and in conclusion bear
always in mind, _it is the simplest form of camera work and the most
difficult_, making the utmost demands on your skill, if high-class
results are to be the outcome of its use.
_W. Thomas._
_Lantern Slides._
[Illustration]
A lantern Slide is a transparent positive on glass or other
transparent support, usually 3-1/4 inches square, and is placed in
the lantern in such a way that by suitable illumination and optical
arrangements the image on the slide is made to intercept some of the
light given off by the illuminant from a screen, which without the
screen would be wholly and evenly illuminated by the light.
In viewing a paper print we are really observing the paper by
reflected light, part of our view being intercepted by the image
formed of pigment or reduced metal; the amount of light not being
very great a very thin layer of pigment is required to produce the
appearance of a sufficiently robust image. If the image alone or
with its vehicle be stripped from a good print on paper this image
viewed by transmitted light will be found to be extremely faint, far
too faint to be of any use as a "transparency," and also too thin to
be of any use as a lantern slide. On the other hand, what we know as
a "transparency," such as is often used for window decoration,
backed, perhaps, with ground glass, would be found much too dense or
robust for use as a lantern slide. In density, then, a "slide," as
it shall hereafter be called, comes between the image on a paper
print and that on a "transparency." In "gradation," or gamut of
tones, the slide ought to be superior to either the paper print with
its almost absolute clearness over large areas, or the transparency
with its dense shadows and its comparatively heavy lights. In fact,
in a good slide we have every grade of deposit from perfect
transparency to nearly complete opacity. But the extremes must be
very sparingly present, and the transition from one tone to another
must be gradual, all intermediate notes between highest and lowest
should be represented.
Other qualities go to make the perfect slide; the metallic or other
deposit forming the image must be in the utmost degree fine, no
approach to "grain" must be perceptible even under the highest
magnification. The colour, or "tone," must be not only pleasant but
appropriate.
The loss of light in its journey from the illuminant to our eyes is
enormous; the disc on the screen is simply a greatly magnified image
of the light, and here is great loss; add to this the interception
of some light by the opacity of the slide, and the fact that much
more is lost in reflection from the screen, and absorption by the
screen, and it is easy to realize that the image from the screen
reaching our eyes is vastly less bright than that reaching the eye
when, for instance, we examine a slide in the hand by transmitted
light. And loss of light means increase of contrast, so that a
slide which would seem about right in gradation in the hand would be
altogether soot-and-chalk as a screen-image. So too if we have in
the slide already shut out much light, by making the slide foggy, or
over dense, it is easy to see that when the image reaches our eyes
from the screen this vicious opacity will be immensely increased in
its mischievous properties. The first style of slide gives
screen-images sometimes called "midsummer snow-scenes"; the other
slide is simply called "foggy." Both must be assiduously avoided.
It need hardly be said that the plates prepared by some processes
are more likely to yield good slides, such as are described above,
than plates prepared by other processes; no one process can claim to
possess in itself superiority in all respects. Collodion, for
instance, is less apt to give foggy slides, and it is easier to
intensify than gelatine, but it is also more prone to give "hard"
images. Collodion is at its finest in the form of collodio-bromide
emulsion, which gives slides remarkable for fineness of grain, for
clearness, and for richness of tones; but when we have to copy in
the camera, the operation with collodion emulsion is protracted,
unless we have bright daylight or a condensing arrangement, which
with large negatives is often out of the question. On the whole it
may be taken that gelatine-bromide emulsion is the process to be
recommended, not only on account of its convenience and celerity,
but in view of the many inherent points of excellence that it
possesses. In any case, want of space will cause us to confine
attention here to that process, and any one mastering the use of
gelatine-bromide slide-plates will have nothing to fear from
competition with other processes in all-round work. The writer has a
leaning towards slide-plates as slow as he can procure them, because
slowness almost always goes hand in hand with fineness of grain and
freedom from fog.
There is one point of importance that should be noted in working
with gelatine for this purpose. Distilled water should be used if
possible for all solutions. Tap water--especially hard water--is apt
to produce with the gelatine a certain amount of scum which, if
present in any appreciable degree, cannot fail to affect the quality
of the slides; but treatment with an acid alum bath as described
later has a very salutary effect in removing any scum that may have
formed during the "liquid" operations.
In the mechanics of making a slide from a negative we have only two
methods to consider. If the slide-image is to be the same size as
the negative, or a part of the negative, we print by _contact_, that
is, we put the negative and the slide-plate face to face in contact,
and we expose to light, the negative being next to the light; this
corresponds with making a print on paper. But when we desire to make
a slide including all the subject of a negative larger than a
slide-plate, or, in fact, when we desire to alter the size of the
image at all, we copy the negative "in the camera." The simplest
method of doing this is to fix up the negative so that it is evenly
lighted and make a photograph of it in a camera; but the adjustments
necessary for such an operation would be found awkward, and so a
"reducing camera" of some kind is generally used. Many such cameras
are on the market, and consist of devices for holding the negative
in a suitable position with regard to a small camera furnished with
a lens and a dark slide holding a lantern plate. Either the
negative-holder or the camera should have possible movement in all
directions vertical to the optical axis of the whole, and in
addition it is often desirable to have a certain amount of movement
in other planes, in order to correct certain optical defects that
are sometimes found in negatives. The writer has for many years used
a small camera with its front stuck into the front of a large
camera, one or other of these cameras has every necessary movement.
The device is figured here.
[Illustration]
Whatever arrangement is used the end of the apparatus bearing the
negative is directed towards a good and even light; and it is well
to place about two inches in front of the negative towards the light
a piece of finely ground glass for ordinary negatives; this glass is
with advantage omitted with extra dense negatives.
It goes without saying that the exposure, whether we are working by
contact or in the camera is of the utmost importance; but it is not
possible in an article such as this to give even an approximate idea
of the exposure suitable under any concatenation of conditions. The
best clue to exposure is to be found in development, and in results.
It is necessary to know what happens after normal exposure with a
given developer, and then if any variation is noticed to alter the
exposure. If a plate develops more rapidly than the normal, it may
fairly be deduced that the exposure has been too long; but if we are
dealing with a specially contrasted negative it is better so. On the
other hand, when we are dealing with a thin negative, especially if
the scale of gradation is short, we require an exposure less than
what would under normal conditions lead to complete development in
the normal time. And again some plates require to be developed to a
greater point of apparent density than others; this is a matter of
experience. Briefly put, there is no royal road to good
slide-making, experience is necessary.
In actually making the exposures certain points must be kept in
mind. If we are copying in the camera with daylight as illuminant it
is very important to use the light from the north; if we use other
light we shall be much put out on most occasions by awkward
variations of the brightness. A very large number of operations are
rendered nugatory by carelessness in this matter. Even the most
experienced worker will find it impossible to expose plates with
anything like accuracy when he has to deal with direct sunshine at
one time, thin white clouds at another, and dark clouds at a third.
And in making exposures by contact the beginner must be fairly
accurate in judging the time of exposure and the distance from the
radiant. A good plan is to tie to the gas jet a piece of cord having
knots at convenient intervals, such as at 9, 12, 18 and 24 inches,
and in making an exposure to use these knots as guides to the
distance; moreover, the law of "squares of distance" must be
remembered; the intensity of light varies inversely as the square of
distance from radiant to receiver, provided, of course, no optical
arrangement is introduced to modify the path of the rays.
Consequently, for example, if ten seconds is found to be a proper
exposure at nine inches from the light, the corresponding exposure
at eighteen inches will not be twenty, but forty seconds (9^2=81.
18^2=324). And as it is sometimes awkward to hold the frame and
attend to a watch at the same time, a metronome, ticking seconds,
will be found convenient, or a clock with a second hand may be
placed where it can be seen during the exposure. A landscape slide
without clouds, if the horizon is in the picture, is usually
considered a failure, and has been dubbed "bald-headed." Really good
workers often put clouds into slides by "combination printing,"
which in some cases is comparatively easy, in others very difficult.
If we are working by reduction from a good-sized negative, with a
fairly even horizon, the difficulty is not great. The landscape part
of the negative is first exposed, the sky being masked if necessary,
and a cloud negative is then substituted for the landscape negative,
a part of the former being masked to correspond with the landscape
on the latter, and a second exposure is made on the same
slide-plate. Admittedly in all cases this requires "some doing," in
many cases it is extremely difficult. An easier, if less
"sportsmanlike," method is to make the cloud slide on a separate
slide-plate, and to use the latter as a "cover-glass" for the slide.
The cloud may cover the whole of the second slide, and that part of
it not required may be wiped out by means of a reducing solution,
used with a brush, such as the ferricyanide and hypo one described
later. This method will be found useful even in contact slide
making, but it also requires not only good taste in the selection of
the cloud, but some deftness in manipulation; but the neat-handed
beginner need not fear to make the attempt.
DEVELOPMENT.
It has already been stated that judgment of exposure is a matter of
experience, and that results are the best criterion; here follow
some more explicit statements on the same matter.
Whatever plate or developer is used, and whatever the time occupied
in complete development:
_1st._--If by the time the high-lights are sufficiently
strong the shadows are too dense or blocked, the plate has
been under-exposed.
_2nd._--If by the time the high-lights are sufficiently
strong the shadows have not attained sufficient density, or
are veiled, the plate has been over-exposed.
_3rd._--If at the same moment the high-lights show
sufficiently and the shadows are transparent but
sufficiently plucky, the plate has been properly exposed.
_4th._--With a normal negative the normal exposure is the
proper exposure; but (_a_) a negative abnormally strong in
contrasts will require an abnormally long exposure; and
(_b_) a thin negative, or one with a very short scale of
gradation from densest to clearest, will require an
abnormally short exposure, with probably some
after-treatment in the direction of "intensification."
Ambitious slide-makers generally aim at warm-toned slides for
pictorial effect, and rightly. But slides intended for scientific
purposes are generally better when cold in tone, the definition is
usually better. But whatever the aim, a good tone of one kind is
preferable to a poor one of another kind, and the beginner should
first make sure of getting a really good cold tone, which is
comparatively easy, and then try his "'prentice hand" on warm tones.
Warm tones are obtained by using greatly super-normal exposures and
greatly restrained developers; and the danger probably lies in the
fact that the long exposures are apt to lead to fog, and the great
restraint to over-density in the shadows, the latter especially when
the exposure has not been quite long enough for the developer used;
herein probably lies the whole secret of warm slide-making. If we
aim at really warm tones and use developers suited to such design,
we must on no account stint the exposure.
COLD TONE DEVELOPING SOLUTIONS.
[Illustration]
The classical solution for cold tone slides is a solution of ferrous
oxalate in potassic oxalate. Of all developers it is most free from
fogging propensities. It is made from so-called "saturated
solutions" of proto-sulphate of iron and potassium oxalate. Thus,
into a bottle put a quantity of iron proto-sulphate, and pour on
about three times its weight of water containing a dram of sulphuric
acid to each pint. Shake well, and keep always at about 60° Fahr.;
some of the iron must always be visible in the bottle, if not, more
is to be added. The crystals of iron salt must be green and not
rusty in colour. This is the "iron solution."
The "oxalate solution" is made by dissolving potassium oxalate in
about three times its weight of water. This also must be kept at 60°
Fahr., shaken occasionally, and oxalate added if none is visible in
the bottle.
To make the ferrous oxalate solution we _pour_ one part of the iron
solution _into_ six parts of the oxalate, and it is advisable to add
to each ounce of developer at least half a grain of potassium
bromide; 5 minims of a 10% solution, made by dissolving one ounce of
the bromide in about 9 ounces of water, and then making up to 10
ounces--all chemical.
In about four minutes or less this ought to fully develop a properly
exposed plate. If the development is much shorter the slide is apt
to have an unpleasant greenish tone, a result that may also follow
the use of an inordinate amount of bromide in the developer. The
developing solution may be made in quantity greater than is required
for one plate, and may be used several times if a little of the
surplus and fresh solution is added when the quantity in use becomes
slow in action.
For really fine cold black tones the following formula by MESSRS.
ELLIOTT & SON will be found admirable:--
A
Metol 40 grains.
Soda sulphite 1 ounce.
Water 8 ounces.
B
Potassium carbonate 120 grains.
Ammonium bromide 24 "
Potassium bromide 48 "
Water 8 ounces.
The developing solution consists of equal parts of A and B.
If either of the above developers is to be used, the exposure is to
be kept down as compared with the exposure to be followed by
developers intended for very warm tones.
The two developers which follow next, require about the same
exposure as the two already formulated. "Ortol" is a reducing agent
quite lately introduced by Mr. Hauff, of Feuerbach in Germany, and
Mr. Hauff's agents in this country are Messrs. Fuerst Bros., of
London. "Ortol" gives the finest tones of the warm black type that
we have as yet come across, it is singularly free from fogging
propensity, and the tones do not easily degenerate into the greens
so apt to occur after severe over-exposure with other "black"
developers. We suggest a simple formula:--
A
Water 20 ounces.
Metabisulphite of potassium 75 grains.
Ortol 150 grains.
B
Water 20 ounces.
Soda carbonate 3-1/2 ounces.
Soda sulphite 2-1/2 ounces.
To make the developer, take one part of A, one of B, and one of
water, and to each ounce of the mixture add one and a half or two
grains of potassium bromide. The development of a properly exposed
slide will take two or three minutes, and the result will probably
be highly appreciated.
The above is worthy to stand alone as representing developers for
warm black tones, but the following works well. (Messrs. Elliott &
Son.)
A
Hydroquinone 80 grains.
Soda sulphite 1 ounce.
Potassium bromide 15 grains.
Water 10 ounces.
B
Caustic soda 80 grains.
Water 10 ozs.
The developing solution consists of equal parts of A and B, and the
plate may be fully developed in about two to three minutes.
It has already been stated that in order to obtain really warm red or
reddish tones by development, it is necessary to give very long
exposure, and to use a developer very much restrained. It is further
found that carbonate of ammonia has a considerable effect in
reddening the developed image, and so we now come to procedure based
on these lines. Carbonate of ammonia is found in commerce in the
shape of "chunks" more or less square. If one of these is pared with
a knife--unless the sample is quite fresh--the outside will be found
to be a soft amorphous powder, the inside a clear, very hard crystal;
the clear crystal is in development an "accelerator," though a very
weak one, the outside substance is a restrainer. Probably both the
inside--sesquicarbonate--and the outside--bicarbonate--are useful,
and the best plan is to make a ten per cent. solution of the
substance as obtained from a good chemist--not druggist. Of this
solution one grain of the salt is represented by ten minims. If now
we take an ounce of A, and one of B of the last formula, and if we
add to the ounce of A 3 grains of ammonium bromide, and to the ounce
of B 3 grains of ammonium carbonate, and if we have given a proper
exposure and develop with equal parts of the A and B modified as
above, we shall get a slide of rich chocolate colour; and if we
double the proportions of carbonate and bromide, and expose still
longer, we shall get a slide still ruddier in tone, even to red. But
there is always danger of fog, and of clogged shadows, and this must
be reckoned with. There is a more certain and less dangerous way of
getting handsome tones, which shall be described presently.
Gelatine slides are always fixed in hyposulphite of soda, about one
part by weight to six parts of water; after this they must be well
washed, say five minutes under a good rose tap, or in many changes
of water in a dish for an hour, and every slide should be treated
with a saturated solution of potash alum, of which each pint should
contain a dram of hydrochloric acid.
Very many, if not most, slides are all the better for just a touch
of a "reducer" such as follows:--The ordinary "hypo." solution is
weakened with about four times its measure of water, and the plate
is soaked for a minute in this. A few drops of a ten per cent.
solution of potassium ferricyanide are put into the measure, and the
hypo. mixed with it, and the whole allowed to work on the plate for
a short time, carefully watched. Of course a weak slide must not be
thus treated, but it is often a good plan to develop slides to such
a point that they will permit of this treatment.
On the other hand it is often advisable to keep a slide thin in
development, for instance, when the negative wants pluck, and
intensification is indicated; or when we wish a good warm tone after
a "black" developer such as our metol formula: a good average
treatment is as follows:--
Take half an ounce each of ammonium chloride and mercury bichloride
and dissolve in 16 ounces of water, soak the slide in this till it
is bleached. Wash well and treat with weak liquid ammonia, or a
solution of soda sulphite, or of metabisulphite of potash, or fresh
lime water. This will strengthen the slide and give it in most cases
a fine rich colour. It is important to let these solutions act
thoroughly, and not to stop the action half-way. The writer
considers this the best and safest way to obtain warm tones, the
reader may find out for himself which of these solutions produces
the tones he chiefly affects.
Crystal varnish is _not_ wasted even on a gelatine slide.
In conclusion, it must be realized that the screen-image is a
greatly enlarged edition of the slide-image; any small defect on the
slide is a huge one on the screen. Consequently the slide-maker must
sedulously cultivate cleanliness and manipulative care.
_Andrew Pringle._
[Illustration: Fishing Smacks. W. Thomas. ]
_How to make Enlargements._
[Illustration]
Enlargements may be made by daylight, or by artificial light, and
there are two methods of producing them, namely, by enlarging direct
from the negative on to a sheet of bromide paper; or by first making
a small transparency, and from that producing an enlarged negative
upon a slow dry plate. The first is the method usually adopted by
amateurs, probably because the necessary operations are fewer, and
perhaps more simple. The second plan, however, possesses the
advantage that the prints may be made by any process, be it carbon,
platinum, or silver, and thus a great variety of effect obtained.
The first point however that the reader must decide is whether he
will work by artificial light or by daylight. Each may be said to
possess certain advantages, and with many the question resolves
itself into one of personal convenience. Artificial light is, or
should be, fairly constant in intensity, and if adopted there will
probably be less waste of material through miscalculation of
exposure. But if the source of light employed be other than a mixed
jet, or the arc-light, if in fact it be of low intensity, negatives
of a somewhat delicate type will be required in order to produce
enlargements of the highest excellence. If the negatives are dense
and strong, illuminants of low intensity, like oil or gas, do not
possess sufficient penetration to duly register the denser portions
of the negative, and the enlargements so made are apt to be
deficient in half-tone, and hard. With well-graded negatives of
suitable quality, however, most excellent enlargements may be
produced by artificial light. When artificial light is used work may
be carried on at any time of day or night, in winter or summer.
Those who adopt the daylight plan will, of course, be subjected to
greater restrictions, at any rate, during the winter months, but
amateurs who take a real interest in the work will do well to adopt
the writer's plan, and provide themselves with apparatus for each
method of working.
ENLARGING BY DAYLIGHT.
There are two ways of enlarging by daylight. The first involves the
exclusion of all actinic light from a room except that which passes
through the negative. The alternative method of working is to employ
an ordinary enlarging camera, such as are made by Middlemiss, or
Lancaster. It is desirable, but not necessary, if the first plan be
adopted, to secure the exclusive use of a room. One with a northerly
aspect should be chosen, for if sunlight falls upon the window
shadows will at some period of the day fall upon the negative, and
produce unevenly lighted enlargements. An upper room will be most
suitable, and, if the light be a northern one, and there are no
trees or buildings to obstruct the view, a reflector may be
dispensed with. If external objects intervene, however, one must be
employed. It should be fixed outside the window-sill, at an angle of
45°, and should be capable of adjustment. Let it be _the full width
of the window_, and _securely fixed_ for obvious reasons. A
plate-glass mirror is effective, but expensive. A large drawing
board painted dead white also answers well, but should not be left
outside exposed to the weather.
[Illustration: Fig. 1.]
[Illustration: side view ditto]
Provision for excluding the light from the room is best secured by
making a wooden frame large enough to fit closely against the window
frame. Upon this a piece of stout calico should be tightly strained
and secured with tacks. It should then be sized, and when dry will
be as tight as a drum; it must then be covered with two thicknesses
of stout brown paper pasted on. The frame is shown complete in Fig.
1. Now at AA. BB. screw two strips of wood, the distance apart
must be regulated by the size of the negatives to be enlarged. The
ordinary camera is intended to be used as the enlarging camera, and
the distance from C. to C. should be just equal to the size of the
back portion of the camera. On the lower rail BB screw a piece of 9
in. board to form a shelf or support D. for the enlarging camera.
Make a frame E. of 1/2 in. wood 1 in. deep, the same size as the
back of the camera, and screw to the shelf and top rail AA. Now
carefully cut away the brown paper and calico from the inside of
this frame, at the part marked H. and paste strips of brown paper
round it so as to prevent any light passing except through the
opening H. A strip of felt should be tacked all round the large
frame to prevent any light from creeping in between it and the
window frame. A couple of turn buttons will keep it in position. A
_firm_ table should be placed against the window close up to the
wall to form a support for the enlarging easel. Now a little care
must be taken in fitting up this portion of the apparatus, and it is
better to have something more exact than the propped-up drawing
board or printing frame, which is sometimes recommended. Get a
carpenter to run out two V shaped rails as shown in Fig. 2 at CC.
They should be about the length of the table, and screwed down upon
it. Procure a cheap drawing board about 15 x 12, and to the under
side affix two pieces of wood with V shaped grooves corresponding in
angle to the rails. This forms the base of the easel AA. Make a
frame 22 x 20, or rather larger than the biggest enlargement that it
is desired to produce. It should be constructed of 1/2 in. wood, and
be 2 in. deep. It is shown in Fig. 2 at 1 DDDD. Now make, or get
made, a set of carriers EE, the largest of which should just fit
into the frame. Narrow fillets of wood screwed each side will afford
a rise and fall adjustment, and a thumb screw at G will fix the
carrier in any desired position. To obtain the cross-movement screw
the frame DDDD to a piece of inch board 5 in. wide HH. Place this
exactly in the centre of the base board, and screw fillets II of 1
in. wood to each side. This will afford a cross motion, and a thumb
screw at J will fix the carrier frame when the necessary adjustment
has been made.
[Illustration: Fig. 2.]
In setting up an enlarging apparatus, whether it be for day or
artificial light, it is absolutely essential to preserve the
parallelism of its various parts, otherwise it will be impossible to
produce sharp or evenly defined enlargements, and for this reason I
have described somewhat fully the construction of a suitable easel.
I may add that it will serve equally well for either daylight or
artificial illumination, and I strongly advise the reader to
construct, or have constructed, an easel on the lines I have laid
down. With it either direct enlargements on paper can be produced,
or plates may be used and enlarged negatives made. The easiest way
of holding the paper during exposure is to procure two sheets of
clear glass, patent plate is most suitable, sandwich the bromide
paper between them, and secure with two strong bands of elastic. The
complete apparatus in position for working is shown at Fig. 3.
[Illustration: Fig. 3.]
[Illustration: Fig. 4.]
The second method of enlarging by daylight is by employing an
ordinary enlarging camera. The same conditions as to lighting, etc.,
should be sought for, and the most convenient way of working will be
to tilt the camera at such an angle as that the negative receives
unobstructed illumination from the sky. A reflector in this case
will not be necessary, but a piece of very finely ground glass
should be placed about an inch in front of the negative in order to
soften and diffuse the light. This method of working is shown in
Fig. 4.
ENLARGING BY ARTIFICIAL LIGHT.
Before describing the actual process of making an enlargement it
will be well to deal with the alternative method of working, namely,
by artificial light, as the manipulations of the sensitive material
used are the same in either case. Practically the most satisfactory
way of working by the latter method is to use an enlarging lantern
properly fitted with a condenser. The general principles of such an
apparatus are identical with those which obtain in an ordinary
optical lantern. Methods which dispense with the use of a condenser
are more or less unsatisfactory, and should be avoided. In the space
at the disposal of the writer it is not possible to give directions
for the construction of an enlarging lantern, but those who may
desire to make their own, will find full instructions and working
drawings in "[6]Practical Enlarging."
[6] A Iliffe & Son.
[Illustration: Fig. 5.]
Enlarging lanterns of excellent quality are obtainable commercially,
but for the guidance of the uninitiated it may be useful to refer a
little in detail to one or two important points with regard to their
construction. The condenser will first claim attention. The ordinary
pattern consists of two plano-convex lenses mounted as shown in
section at Fig. 5. This answers fairly well with the smaller sizes,
but when the diameter of the condenser is large, a good deal of
light may be lost. The interposition of a small meniscus or
plano-convex lens, in the manner first suggested by the late J.
Traill Taylor, and shown in Fig. 6, will be found a great
improvement. Its proper position will be at the point where the
divergent cone of rays proceeding from it just covers the large
condenser. In our own practice we always place a diffusing screen of
very finely-ground glass in front of the condenser at EE The
diameter of the condenser is governed by the size of the negatives
to be enlarged, it must be of sufficient size to include the longer
sides of the plate within its circumference without cutting the
corners. If it is much larger than this, an unnecessary loss of
light will occur, because only that which passes through the
negative can be utilized.
[Illustration: Fig. 6.]
THE ILLUMINANT.
The smaller and more intense the light, the nearer we approach to
the ideal projection illuminant, and the better will be the
definition of our enlargements. The arc light most nearly fulfils
the desired conditions, and if it be available it should certainly
be employed. Next in point of utility comes the limelight,
preferably in the form of the mixed jet, and those who understand
its manipulation are recommended to adopt it, but the majority of
amateurs will probably find it more convenient to use either
incandescent gaslight or an oil-lamp. Parallel wick-lamps should be
avoided on account of the unequal illumination they produce, and if
oil must be used a good circular wick burner will be found more
suitable. Where house-gas is available the incandescent gaslight is
however much to be preferred. The light is perhaps not so powerful
as that given by a really good parallel wick-lamp, but it is far
more actinic and penetrating. The writer has used this light with
great satisfaction, and therefore has no hesitation in recommending
it. Some workers have been troubled by the appearance of an image of
the mantle on the screen, but this can usually be got rid of by a
suitable adjustment of the lenses and the light, and in any case by
the interposition of a piece of ground glass between condenser and
negative.
THE CHOICE OF THE LENS.
It is commonly stated that the lens with which the original negative
was taken will serve equally well to enlarge it, and in the abstract
the statement is perhaps not inaccurate. But assuming that a lens of
a focus equal to about 1-1/4 times the base of the plate has been
used, it will be found that better results, both in regard to
definition and equality of illumination, will be obtained by
substituting a lens of rather longer focus, for example a half-plate
lens for enlarging from quarter-plate negatives. This, although
applying to both methods of working is particularly desirable when
enlarging by artificial light, for an objective of small diameter
and short focus cannot possibly pick up or receive the whole of the
cone of rays proceeding from the condenser. A reference to Figs. 7
and 8 will explain why this is so. In Fig. 7 we see what happens
when a lens of too short a focus is used, but when one of longer
focus is substituted, the whole of the cone of rays passes through
and is utilized (Fig. 8). In selecting a lens one should be chosen
which has a sufficiently large diameter to permit the apex of the
cone of rays from the condenser to pass through. This point will, of
course, vary with the degree of amplification, and in order to
obtain the best results optically, the distance of the light from
the condenser must be carefully adjusted in every case, and a clear,
evenly lighted disc obtained before inserting the negative to be
enlarged.
[Illustration: Fig. 7.]
[Illustration: Fig. 8.]
With regard to the type of lens, one of the rapid rectilinear form
will answer well. A portrait lens is often used on account of the
brilliancy of image, but although it answers well for enlarging
portraits, the roundness of its field makes it less suitable for
landscapes unless it is considerably stopped down. If the very
finest results as regards definition are required, then one of the
now numerous flat-field lenses should be used. The writer can from
practical experience speak well of the Ross-Goerz and the Cooke
lens. The latter is perhaps preferable for working with artificial
light on account of the larger diameter of the back lens. Wide-angle
lenses, on account of their small aperture and short focus, are not
suitable for use with a condenser, both for the reasons given, and
on account of the difficulty in focussing owing to the small amount
of light transmitted. When daylight is used, however, there is less
objection to their employment.
[Illustration: Fig. 9.]
Before leaving this part of the subject it should be noted that in
regard to preserving the parallelism of its parts the same care in
erecting and fitting up the enlarging lantern must be observed, as
was insisted upon in the description of the apparatus for daylight.
It will be found convenient, therefore, to mount the lantern on a
base similar to that upon which the easel rests, so that both may
move on the same rails. The easel described for daylight enlarging
will serve equally well for working by artificial light. The
complete apparatus is shown at Fig. 9, which is a reproduction from
a photograph of the apparatus constructed and used by the writer.
THE NEGATIVE.
In general practice one may find it necessary at times to enlarge
from negatives of very dissimilar types, but there is no reason,
when the negatives are to be produced with the special object of
subsequently making enlargements from them, why care should not be
taken to make them of a suitable character. Thin delicate negatives
should be enlarged by artificial light; dense, strong ones by
daylight. If the negatives are very strong it will be difficult to
produce soft and well-graded enlargements with a weak illuminant,
the light not being sufficiently intense to properly penetrate the
high-lights. A soft and clear negative, with good gradation, fully
exposed, and neither exhibiting patches of clear glass shadow devoid
of detail, nor of hard impenetrable high-light, will be found most
suitable. Fog should be avoided, as also should the yellow stain
produced by pyro when improperly used. Not that the pyro developer
is unsuitable, for if sufficient sulphite is used, and the quantity
of pyro kept down, negatives of very beautiful quality for enlarging
purposes may be produced. Great care should be taken to avoid
bubbles, stains, scratches, or any kind of mechanical defects, as
such when enlarged become painfully obtrusive, and spoil the effect
of the best work. It will be found a good plan to bind the edge of
the negative before enlarging it with a strip of lantern slide
binding, so as to cover the clear glass rebate mark. If this be
omitted the margins of the enlargement may become fogged by the
lateral spreading action of the light. No hand-work should be
attempted on the original negative, for any such treatment will
become painfully apparent in the enlargement. If retouching be
deemed necessary, it should in the case of a direct enlargement be
executed upon the print itself, or upon the enlarged negative or
preferably upon the enlarged transparency, when that method of
reproduction has been adopted.
DIRECT ENLARGEMENTS.
The following concise instructions for enlarging upon bromide paper
will apply equally to the daylight or artificial light methods of
working. In the first case the negative is placed in the dark slide
of the camera, both shutters being drawn fully out. The camera is
then put upon the shelf close up against the opening in the shutter,
as shown in Fig. 3, any light creeping in between shutter and camera
being blocked out with the focussing cloth. If the enlarging lantern
is used the negative will be placed in the carrier, just in the same
way as a lantern slide, with the film side towards the enlarging
lens. Now the first difficulty that will be experienced will be to
get the enlarged image of the required size. It will be well to
content ourselves at the outset with a moderate degree of
enlargement, say from 1/4 plate to 12 × 10, and when proficiency is
acquired, larger sizes can be attempted. At first we shall probably
not succeed in getting any image at all. In adjusting the various
parts of the apparatus we shall find the work easier if we remember
that the nearer we place the lens to the negative the further will
it be necessary to move the easel from the lens, and the greater
will be the enlargement. A useful table of enlargements will be
found in the "British Journal Almanac," showing the distance of lens
from negative, and negative from paper, for almost any required
degree of amplification.
Now it will be found much easier to focus the enlarged image by
looking at it through a piece of finely ground glass, than by
receiving it on a piece of card or paper, and the adoption of the
easel plan of focussing previously described will enable this to be
done. The ground surface of the glass (which must be of the same
thickness as the piece behind which the paper is to be exposed)
should be away from the lens and towards the person focussing, when
it is placed in the carrier of the easel, it being retained in
position with the spring S., Fig. 2. Focussing must be carefully
performed, and is effected by sliding the easel to and fro upon the
runners, and which should have been previously rubbed with
blacklead.
Bromide paper is made in several varieties, such as smooth, rough,
snow-enamel, cream crayon, etc., and is put up either in tubes, or
packed flat. The latter is decidedly the more convenient, it being
somewhat difficult to take the curl out of paper that has been
rolled. The choice of paper is a matter of taste; for landscape work
the rough paper or the cream crayon will perhaps be found most
suitable. For finer work, and some classes of portraiture the enamel
will prove effective. Rough paper is better for strong broad
effects, smooth for more delicate work and the rendering of fine
detail. The coated side may be distinguished by its tendency to curl
inwards. The easiest way of exposing it is to procure two pieces of
patent plate glass of the same thickness as the focussing glass,
sandwich the sheet of paper between the two, and secure with strong
elastic bands. This will hold it quite flat during exposure, and
will not disturb the actinism of the lens or impair the definition
of the enlargement.
DEVELOPMENT.
This part of the work of producing an enlargement will only be
lightly dealt with, as the subject is fully treated elsewhere in
this volume. The writer prefers the ferrous-oxalate developer for
bromide enlargements to any of the more recently introduced
developers, but as it requires more skill and judgment to employ it
with complete success, beginners may find it better to use amidol or
metol, either of which when properly used gives excellent results.
Hydrokinone we do not recommend for this purpose owing to its
tendency to give rusty blacks in the event of over-exposure, or
undue hardness if it has been too short. With amidol a pure delicate
black is easily obtainable, and it is moreover a very simple
developer to use. Our own plan is to employ a weak solution and give
a full exposure, and by these means we find no difficulty in
obtaining good gradation and pure blacks. The dish used for
development must not be used for other developers or stains will
probably occur. Although a quick appearance of the image is usually
a characteristic of amidol, no trouble will be experienced when the
developer is used in the way we advise, for the picture will be
found to develop slowly and regularly, and gradually grow in
strength. Quick development by this method would be an indication of
over-exposure. A correctly exposed enlargement should take about ten
minutes to develop. One stock solution only is necessary. It will
keep indefinitely.
Sulphite of soda 1 ounce.
Citric acid 20 grains.
Distilled water 40 ounces.
Potassium bromide 15 grains.
To each ounce of the above add, just before using, three grains of
dry amidol. The exposure must be accurately timed. It is, however,
impossible to give useful information on this head, unless such
varying factors as the rapidity of the paper, the intensity of the
light, the aperture of the lens, and the degree of enlargement are
known. The best plan is to cut one of the sheets of bromide paper
into twelve strips, and on these make several test exposures,
carefully noting the duration of each. It is better (at any rate for
a beginner) not to vary the constituents or strength of the
developer, but to increase or diminish the exposure until a good
result in colour and tonality is obtained. By entering full details
relating to the production of a successful enlargement in a
notebook, great exactitude in working will be obtained, and there
need be little or no waste of material when additional enlargements
have to be made from the same negatives at a future time.
[Illustration: DRIFTING STORM CLOUDS. W. THOMAS.]
A glass dish, though expensive, is very suitable for developing, for
being flat-bottomed a minimum of solution can be used, and moreover
if the dish should be dirty, the fact is at once apparent. The
exposed paper should be soaked in water for a few minutes until
uniformly wetted, and any air-bells removed with a camel-hair brush.
The water is then poured off, and the developer applied in an even
wave, so that the whole of the paper is covered uniformly and
quickly. The image will appear slowly, and gradually gain in detail.
When all the detail has appeared it may still appear lacking in
vigour and contrast, but this will come if sufficient time be
allowed. _Development should not be stopped until the print is of
the full strength required_, but it is not advisable to allow it to
become much darker than it is desired to appear when finished,
because there is very little loss of strength in the fixing bath.
If the image flashes out immediately upon the application of the
developer, the paper has been over-exposed. A strong dose (one or
two drams) of ten per cent. bromide added to the developer may help
to save it, but the enlargement will probably look poor and flat and
of bad colour when finished. If the picture appears very slowly, and
refuses to gain in strength, under-exposure is the cause, and two or
three drams of a ten per cent. solution of sulphite of soda may
improve matters, but as a rule the most satisfactory plan will be to
make another exposure. With regard to the strength of the developer,
that given is very suitable for negatives of normal density, but
some papers may require a little more amidol, the appearance of the
finished enlargements will guide the reader in regulating the
quantity to suit the particular paper with which he may be working.
The enlargement should be washed in plenty of running water from the
tap to arrest development, and then fixed in:--
Hyposulphite of soda 4 ounces.
Water 20 "
A quarter of an hour should be allowed for fixation, but it is
better to use two baths, giving ten minutes in each. After washing
in running water for a couple of hours they may be hung up by one
corner to dry, or pinned down to a blotting board.
Enlargements produced in the manner described should be of a pure
engraving black colour, and if they are mounted upon _pure_ boards
with _freshly_ made Glenfield starch, they should prove permanent.
Enlargements are frequently toned to various shades of brown and
red, generally by the employment of the uranium-toning bath.
Although the colours so obtained are often very artistic and
pleasing, no reliance can be placed upon the permanence of an
enlargement so treated, and the writer strongly recommends that when
warm coloured prints are desired, an enlarged negative should be
made and prints made therefrom in carbon, silver, or sepia
platinotype.
ENLARGED NEGATIVES.
The production of an enlarged negative presents no difficulty that
need deter any careful worker from attempting the work. No
additional apparatus to that already described will be required, and
either day or artificial light may be employed. In the first place
a transparency must be made from the small original negative. It
may be made either by contact or in the camera, preferably the
latter as then the acme of sharpness will be obtained. If, however,
the reader is acquainted with the carbon process he cannot do better
than make a carbon transparency, for such are specially adapted for
the production of enlarged negatives. Many, however, will prefer to
make the transparency on a bromide plate, and as this is the part of
the process which requires the greatest amount of care, and as _in
fact_ the _quality of the enlarged negative will entirely depend
upon the character of the small transparency_, it is necessary to
deal with the matter somewhat in detail. Preconceived ideas of
quality based upon the appearance of a good lantern slide must be
put aside, for that is not at all what is required. What is wanted
is a transparency in which every possible detail existing in the
negative has been reproduced, and which in comparison with a lantern
slide would look rather flat and over-exposed. Every possible
precaution should be taken to avoid granularity or coarseness of
image, therefore a slow plate is almost essential; plates coated
with lantern-slide emulsion are now obtainable, and will be found
very suitable. A full exposure should be given, and a weak and
well-restrained developer employed. These conditions tend to the
production of the qualities desired. Warm coloured transparencies so
produced generally have a finer grain than those developed to a
black or colder colour, but unless the colours produced are fairly
uniform, considerable variation in exposure when making the enlarged
negatives will be necessary, and for this reason it would perhaps be
better for the beginner to aim at the production of good black
transparencies possessing the qualities indicated.
The small transparency, having been fixed, washed and dried, should
be edged with black paper to prevent any subsequent fogging of the
plate, by the lateral spreading action of the light. It is then
placed in the enlarging apparatus, just as in the case of a
negative, and carefully focussed. This operation must be very
carefully performed. The writer uses a thin and very sharp negative
of an architectural subject to focus with, afterwards substituting
the transparency which is to be enlarged. Landscape subjects,
consisting chiefly of foliage, are seldom critically sharp, and it
is then difficult to secure a sharply-focussed enlargement. The
remainder of the operation is extremely simple. In the place of the
ground-glass screen (which in this case should have its rough or
ground side nearest to the enlarging lens) a slow dry plate is
placed, backed with a piece of cardboard covered with black velvet
to avoid reflections and possible fog. The exposure should be full,
and a weak developer employed. Trial exposures may be made on
quarter-plates, coated from the same batch of emulsion, which the
manufacturers will willingly supply, if the purpose for which they
are required is made known. Pyro will be found the most suitable
developer, but it should contain a full proportion of sulphite, and
not be too strong. Exposure and development should be so adjusted
that by the time every possible detail has been developed up, the
plate will not have become unduly dense. If expense has to be
considered, a piece of slow smooth bromide paper may be substituted
for the large dry plate in which case the result will be an enlarged
paper negative. For large sizes, 15 × 12 and beyond, the latter is a
very economical method of working, and the negatives will be found
to yield most artistic prints, and if the operations have been
carried out as described, and the prescribed conditions carefully
observed, the grain of the paper will not show obtrusively or
unpleasantly in the prints.
An alternative method of working, and one which admits of a large
amount of control over the ultimate result, is to make in the first
place a large transparency of the full size that the enlarged
negative is desired to be. All the precautions upon which stress has
been laid should be observed in regard to the choice of plate,
developer, etc.; but in this case the enlarged transparency may be
given a little more vigour and sparkle than would be desirable if
the other method of reproduction were adopted, though in this the
reader must be guided by the particular effect which he may be
seeking to produce in his prints. For this purpose pyro will be
found to be the most suitable developer, in that it permits of a
large amount of control. From the large transparency a negative is
produced by contact printing either upon a plate, or upon a piece of
bromide paper.
The great advantages of the latter mode of working are the
facilities which are afforded for retouching or working upon the
large transparency. Negative retouching is always a difficult
operation to an amateur, for he cannot see the effect of his work
until he has made a print; whereas, in retouching a transparency the
effect produced by each stroke of the pencil or brush is at once
apparent. In the space at disposal it is not possible to describe
the various ways in which improvements can be effected. First there
are the chemical aids of local intensification or reduction. Then
much may be done by the judicious use of a pencil, but the part to
be retouched must first be lightly rubbed with a little retouching
medium in order to make the pencil bite. In extreme cases the back
of the negative may be covered with tissue paper upon which a stump
and chalk may be used _at discretion_.
The novice must not be disappointed with the appearance of his
enlarged negative when it is finished, nor should he form an adverse
opinion of its printing qualities until he has made a print from it.
Confessedly an enlarged negative generally presents a different
appearance to one that has been taken direct, and may even seem to
lack some of those qualities that are commonly regarded as essential
to perfection, but if the final result, the picture, comes up to our
expectations, we may surely dismiss any lingering doubts as to
whether the enlarged negative conforms to certain preconceived
notions of technique, and it should be enough for us to know (and
the fact is incontrovertible) that some of the finest and most
artistic photographs ever shown owe their existence to this method
of production.
_John A. Hodges._
[Illustration: Walberswick. By Rev. A. H. Blake.]
_P.O.P._
[Illustration]
The three letters "P.O.P." are now so widely understood as referring
to the Gelatino-Chloride Printing-Out class of Papers that it may be
said that P.O.P. is known to many who are not acquainted with the
fully-written name of this class of productions.
Also it should be mentioned that when these papers are spoken of as
gelatino-chloride papers it is not to be concluded therefrom that
chloride of silver is the only silver salt present. What they do
actually contain is probably only known to their respective
producers. But generally speaking, it is enough to say that so far as
the ordinary consumer is concerned, the family resemblance is so
strong and chief characteristics so general that the following
directions for using them may be held as generally applicable to the
various well-known brands now on the market. At the outset, however,
it will be convenient to note that for the purposes of manipulation
we may roughly group them into two chief classes--_viz._, the matt
(probably from the German word "matt," _i.e._, dull) and the glazed,
glossy or enamelled. The latter comes to us with a highly glazed,
_i.e._, shiny smooth surface, the former being slightly rough, of a
surface and texture somewhat like that of very finely ground glass.
_Care of the Paper._--The paper is sent out either in the full-sized
sheet, measuring about 24 × 17 inches, or in smaller cut sizes,
suitable for the usual 1/4, 1/2, 1/1 plate and other popular
dimensions of plates. Compared with albumenized print-out paper,
P.O.P. is more sensitive to light; therefore, some care must be
taken to avoid needlessly exposing it to the influence of daylight
or strong artificial light. For example, the printing frames should
be filled as far away from any window as possible, and the prints
examined from time to time either by gaslight or as feeble daylight
as possible.
In handling the paper--cutting it up, etc.--care must be taken to
avoid touching the sensitive surface with the fingers in any case.
The touch of a moist or hot finger is very likely to produce a mark
or stain which is usually irremovable. The paper should be protected
from damp, excessive heat and impure air. If kept _rolled_ in a tin
tube or _flat_ under pressure in the original packages, it will keep
a considerable time--_i.e._, longer than ordinary albumenized paper.
_Printing_ is done in the usual way. Strong diffused light reflected
from the sky or clouds usually gives a better print than direct
sunshine. In case, however, of a thin flat negative--_i.e._, one
with insufficient contrast--good results may sometimes be obtained
by covering the printing frame with a sheet of green glass and
printing in moderately strong sunshine. In hot summer sunshine it is
as well to cover the green glass with a sheet of tissue paper or
fine-ground glass. Care must be always taken when printing in
sunshine or very hot weather to see that the negative itself does
not get too warm, or the paper may stick to it. In this case the
print is of course lost, and the negative, unless varnished, is also
probably seriously damaged by silver stains, which are very
difficult to remove. Printing should not be carried quite so far as
in the case of ordinary albumenized paper because in the subsequent
operations of toning, etc., not so much strength is lost. The same
care as regards shielding from light, etc., should be given to the
prints after they leave the printing frame. They may be proceeded
with at once or kept for some days before being toned, etc., but if
this is done the prints should be kept under pressure. Some workers
have thought that the light action goes on, "continues" in the print
after it is removed from the printing frame. This, however, is not
the generally received opinion.
_Washing._--It is important that the first washing should be done
with some care, or the prints may become stained. The points calling
for attention are (1) running water and plenty of it, (2) care to
see that the prints do not stick together. What is needed is that
the soluble salts should be washed out of the paper as quickly as
possible, and that the prints be not allowed to remain in the water
containing these soluble salts longer than is necessary. Hence the
advantage of running water and plenty of it. The washing water must
not be too cold or the salts will not pass out of the paper quickly
enough; and again, it must not be too warm or the gelatine will
melt. The best temperature is about 65° F., and the limits should
not go beyond 60° and 70° F., and preferably are kept within 60°
and 65° F. As the paper is usually rather stout, it will need
washing in running or constantly changed water for about ten to
fifteen minutes, and in any case must be continued until all milky
appearance of the water ceases. The print at this stage has a
red-brown colour. If it is now passed direct into the fixing bath
without toning it becomes somewhat more yellow, and when dry is
usually a colour somewhat between yellow ochre and sienna.
_Toning_ is usually our next operation, and for this purpose we have
a variety of toning baths recommended by different workers. The
sulphocyanide and gold is perhaps the chief favourite.
1. Ammonium sulphocyanide 10 to 15 grains.
Gold chloride 1 grain.
Water 8 to 10 ounces.
The proper way to mix this bath is to add the gold to the solution of
sulphocyanide a little at a time. The following method will be found
convenient. As ammonium sulphocyanide is somewhat deliquescent, it is
convenient to keep it in solution. Therefore, one ounce of the salt
dissolved in twenty ounces of (distilled or filtered rain) water
gives us roughly a strength of twenty-two grains per ounce. Dissolve
the contents of a fifteen-grain chloride of gold in fifteen drams of
distilled water. To mix a bath, take of the sulphocyanide solution
half-an ounce; to this add eight ounces of water. Now take one dram
of the gold solution and dilute with one ounce of water. Then add
this dilute gold solution a _little_ at a time to the eight ounces of
sulphocyanide solution, and stir well with a glass rod. It will be
noticed that as the gold solution drops into the sulphocyanide
solution an orange-red precipitate is formed, which is redissolved
on stirring. Hence the gold must be added to the sulphocyanide, and
not _vice versa_.
2. Another favourite bath is as follows:--
Ammonium sulphocyanide 22 grains.
Soda sulphite 2 "
Gold chloride 2 "
Water 20 to 25 ounces.
Instead of weighing out two grains of sulphite it is more convenient
to weigh twenty grains and dissolve in two-and-a-half ounces of
water--_i.e._, at the rate of one grain per dram of solution. Thus,
to mix this bath, take an ounce of the above-mentioned sulphocyanide
solution dilute with twenty ounces water. To this add two drams (1/4
oz.) of the sulphite solution. Then take two drams of the gold
chloride solution and dilute with an ounce of water, and add slowly
with stirring as before.
3. Another favourite bath is:--
Sodium chloride (table salt) 60 grains.
Ammonium sulphocyanide 15 "
Gold chloride 2 "
Water 10 to 12 ounces.
Some of the adherents of this bath recommend that the prints be only
washed in running water for a few minutes and then put into the
toning bath. Others advise the prints to be immersed in the toning
bath without any previous washing--_i.e._, straight from the
printing frame.
4. Here, again, is another bath which usually yields excellent
results:--
Soda phosphate 5 grains.
Sodium chloride (table salt) 20 "
Gold chloride 1 grain.
Water 10 ounces.
5. Other workers omit the sodium chloride and increase the phosphate
and get good tones.
Soda phosphate 20 grains.
Gold chloride 1 grain.
Water 10 ounces.
6. Others, again, combine the phosphate and sulphocyanide baths
thus:--
Sodium phosphate 10 grains.
Ammonium sulphocyanide 15 "
Gold 1 "
Water 10 ounces.
The various toning baths mentioned above have one drawback common to
them all in varying degrees--_viz._, that when once mixed and used
they do not keep in good working order longer than a few hours.
7. The following bath claims to have the advantage that it will keep
in working order for a short time at any rate, but the disadvantage
that it cannot be used until it has been mixed twelve to twenty-four
hours.
Soda acetate 60 grains.
Ammonium sulphocyanide 20 "
Gold chloride 1 grain.
Water 12 ounces.
Toning should be conducted in very weak daylight, or what is much
better, gas or lamplight. The latter, being practically constant,
enables the operator to judge the relative colour of the prints from
time to time. Care must be taken so that the prints do not stick
together in the toning bath, and preferably only a few, say
half-a-dozen or so, dealt with at a time, so that each print can be
frequently turned over and examined. The change of colours proceeds
somewhat slowly at first, but when once it begins it seems to gain
in rapidity of rate of change, so that a careful watch must be kept.
Let it be remembered that the print, after fixing and drying, will
appear a little darker and more blue (less red) than when wet in the
toning bath. The temperature of the bath must not be too cold or
toning is very slow, nor too warm or the gelatine may melt and
toning be uneven. From 60° to 65° F. will be found a convenient
range. The prints should not be touched on their printed surface
more than can be helped. The fingers must be quite clean, the
solutions uncontaminated with other chemicals, and a dish set apart
for toning operations only. This dish should always be washed out
well with tepid or cold water before and after use, and when put
away should rest flat, opening downwards, on a shelf covered with a
sheet of clean blotting paper. Many failures in toning are entirely
due to lack of care in details and sufficient attention to
cleanliness.
When toning is judged to be carried far enough, the prints should be
placed in a roomy dish containing a solution of common salt,
strength one ounce to twenty or thirty ounces of water, to stop
further toning.
Fixing is done with a "one in ten" solution of sodium
thiosulphite--_i.e._, hypo. This should be prepared with tepid
water, or some time before use, as the dissolving of hypo in water
is accompanied by a fall of temperature. A convenient method is to
place a couple of ounces of hypo in a clean pint jug, and add about
half a pint of fairly warm water and stir with a glass rod until the
salt is dissolved, then fill up the jug from the tap with cold
water. It is highly desirable to have plenty of fixing solution, and
never attempt to use the same lot twice. Place each print face down
in the bath and submerge by pressing on its back. Again see that the
prints do not stick to each other, and turn each print two or three
times. They should be in the fixing bath not less than twelve or
fifteen minutes, and a few minutes longer will do no harm. At the
end of, say, fifteen minutes, pour away about one half of the fixing
bath and slowly fill up with water. Turn the prints again, and then
transfer them one by one to another roomy dish and wash in running
water for a couple of hours, or in a dozen changes of water every
five or ten minutes. Then hang up to dry, using either clips or pin
a corner to the edge of a wooden shelf or long lath suspended in a
cool, airy place.
_Alum Bath._--Hot weather considerably increases the danger of the
gelatine melting. To meet this trouble the following plan has to be
resorted to:--
8. Dissolve common (potash) alum, one ounce in a pint of tepid
water. Let it stand until cold and pour off gently the clear part
should any sediment appear. After washing and before toning, place
the prints in this alum bath for about ten minutes and _again_ wash
before toning for ten or fifteen minutes in running water.
_The Combined (Toning and Fixing) Bath._--The general weight of
opinion is _not_ in favour of combining these two operations at one
time when reliable results are desired. Nevertheless, there are
times when this method may be found a convenience and yield results
which are all that may be desired. The following bath is a favourite
with some workers:--
9. Ammonium sulphocyanide 15 grains
Table salt 30 grains
Hypo 2 ounces
Water 10 ounces
To this is _slowly_ added one grain of gold chloride in half an
ounce of water. The prints first washed for five or ten minutes in
running water, and placed in the combined bath and kept moving by
being constantly turned over and over for about ten or fifteen
minutes. The longer they remain in the bath the more blue and less
red will they be when dried.
Here is another bath which finds some stout supporters:--
10. Ammonium sulphocyanide 20 grains
Hypo 1 ounce
Alum 30 grains
Water 10 ounces
Shake well, until thoroughly dissolved, then add
Lead nitrate 20 grains
Again shake well and set aside to settle, pour off the clear part,
and add
Gold chloride 1 grain
dissolved in half an ounce of water.
Others recommend a still more simple bath as follows:--
11. Hypo 1 ounce
Water 8 ounces
Gold chloride 1 grain
It is said that this bath gives better results if it is prepared a
few hours before use, _e.g._, prepared in the morning and used in
the evening. Meanwhile, it should be kept away from daylight, and
not in a very cold place.
_Drying and Glazing._--Some workers are of opinion that it is better
to first "rough dry" the prints, _e.g._, by suspending by clips, or
pinning one corner to a strip of wood, etc., and then to wet again
and dry on a rough or smooth surface according as a matt or glazed
final effect is desired. If however, the print has been through the
alum bath (No. 8.) this preliminary rough drying may not be
necessary.
_Matt Surface._--The matt paper when rough dried has a matt or
slightly rough surface, but it may be desired to accentuate the
effect. This may be done as follows:--Thoroughly clean with soap
water and a nail brush a sheet of "fine-ground" glass similar to
that used for a focussing screen. When quite dry, lightly dust it
with fine talc powder (French chalk) and polish off again with a bit
of clean rag. Now slip this plate rough side up into a dish of cold
water, which also contains the print face downwards. Bring the print
and glass into contact under water, carefully avoiding any air
bubbles between them, as the two together are now raised from the
water; firmly, evenly, but lightly pass a squeegee over the back of
the print now in contact with the glass. Then lightly press a sheet
of blotting paper over the print to take up all adhering water, and
set up in a cool airy place to dry, _e.g._, in a passage or between
the door and half-open window. When quite dry, the print will very
probably of itself come away from the glass, but if not, the finger
nail inserted under one corner and a gently backward pull will
separate it from the glass. In place of the fine ground glass,
rougher glass of course may be employed. Some workers also use for
the same purpose a sheet of roughened celluloid. This is more costly
than glass, but being not so fragile may prove cheaper in the end.
_Glazing Prints_ is done exactly in the same way, with the single
difference, of course, that we use a _smooth_ piece of glass,
vulcanite, celluloid, paper maché slab, sheet of ferrotype metal,
etc., etc., in place of a ground-matt, or rough surface. All the
above-named substances have their partizans; perhaps the greatest
favourite being good plate glass free from scratches. In all cases
it is important to attend to two points, _viz._, thoroughly cleaning
the support and waxing it. Various substances and mixtures have been
recommended for giving a glaze, polish to the glass, etc. Many
workers adhere to the powdered talc or French chalk already
mentioned. Others prefer some of the mixtures given below:--
12. Bees wax 20 grains
Turpentine 1 ounce
13. Spermaceti 20 grains
Benzole 1 ounce
A few drops only of the lubricant are applied to the glass plate
with a bit of clean flannel, and well rubbed all over. Then a final
polish is given with a clean old silk handkerchief, or clean dry
wash leather. On no account attempt to strip the print from the
glass until the print is _quite_ dry or failure is more than likely
to arise.
_Mounting._--Care should be taken that the mountant does not give an
acid reaction. Test with litmus paper. Clearly it is no use being at
the trouble of producing a high gloss on the print if we are going
to damp the print and so destroy the gloss in the operation of
mounting. To avoid this, various plans have been adopted.
(1.) If a cut-out mount is used it will suffice if the print be
attached to the mount by glue at the edges only of the "cut-out."
(2.) Another method is to paste down on to the back of the print
before it is quite dry, and while still on the glazing support, a
backing of thin waterproof paper specially prepared for this
purpose. This prevents the moisture of the mountant penetrating to
the print. (3.) Another plan is to use a mountant which does not
contain water. The following mixtures are recommended:--
14. Masticated rubber 10 grains
Benzole 1 ounce
A thin layer of this is applied by means of a short, stiff, flat
hog's hair brush to the back of the print. It is then allowed to
evaporate for a minute or so, and when tacky is applied to the
mount, covered with a sheet of glazed paper, and a roller squeegee
passed over the surface.
15. Saturated solution of bleached shellac in alcohol.
This must be applied as thinly as possible.
16. Le Page's fish glue applied to the edges only of the
back of the print.
A fourth method is to first carefully clean the edges of the glass
surrounding the print still adhering to it. Then to paste down the
mount to the print and let all dry. Then strip the print from the
glass now already mounted. This is, however, a process not to be
recommended, because requiring a long time for the print to dry, as
the evaporation has to take place through the substance of the
mount.
ADDITIONAL PROCEDURES WITH P.O.P.
_Development of Partially Printed Proofs._--This method of procedure
is sometimes a matter of convenience in dull weather, etc. The
printing is to be carried on until one can just see a very slight
indication of detail in the high-lights. It is then washed in
running water for about ten minutes, and then put into a ten per
cent. bath of potassium bromide, and there it remains for another
ten minutes or so. In this bath some of the image seems to fade
away, and generally the print takes on a yellow tinge. The print is
next washed in running water for about ten minutes, and then
developed with ortol, metol, or preferably, hydroquinone. A
considerable variation in the proportions of the constituents of the
developer are possible. In general terms, one may say that a
developer which gives a good black and white lantern slide when
diluted with about an equal quantity of water will give a
satisfactory print.
17. As an example of a thoroughly practical developer for this
purpose we may give just one example:--
A
Hydroquinone 70 grains
Potassium metabisulphite 5 "
Potassium bromide 30 "
Water 20 ounces
B
Soda sulphite 1 ounce
Caustic soda 60 grains
Water 20 ounces
Take equal parts and mix just before use, wash for at least ten
minutes in running water at once after development.
Developed prints may be toned in the combined bath 9, 10 or 11, or
may first be fixed, then _thoroughly_ washed, and then toned and
again washed.
If good results are wanted by the development process it is
important to be careful that the paper is not exposed even to weak
daylight more than can be helped, and not even to strong artificial
light more than is necessary. At the same time it is quite
practicable to do the operation of the bromide bath and developing
in fairly strong gaslight, _i.e._, one need by no means be limited
to the ordinary dark-room light as when developing plates.
Another point worth noting is that it is quite practicable to use
magnesium ribbon for printing. For a rather thin negative it will be
perhaps found sufficient to burn about a foot of the metal ribbon
about three or four inches from the glass. The printing frame should
be set up on edge in the vertical plane. The strip of metal ribbon
is held by a pair of pliers, and ignited at the flame of a candle or
spirit lamp. The lid of a biscuit box just in front of the frame
does very well to catch the white magnesium oxide formed by burning.
It is as well to move the flame of the burning metal opposite
various parts of the negative during the exposure. It will be found
a comfort to wear a pair of rather dark blue glasses during this
operation, as the bright light of combustion prevents one seeing
anything with ease for a little while.
After development the print may be fixed only, and under certain
conditions it is possible to obtain a fairly satisfactory black or
brown colour without toning, but there is usually a slight tendency
towards rather too much yellow.
_Platinum Toning._--This method of toning is a favourite with many
workers. By it a considerable variety of colour tones may be
obtained, from a rich red chocolate brown through sepia brown to a
warm black.
The following toning baths have each their several advocates, and
each worker must discover by experiment the one that gives him the
particular brown colour he prefers:--
18. Potassium chloroplatinite 1 grain.
Water 1/2 ounce.
Add dilute nitric acid (one part strong acid, twenty parts water)
drop by drop until the mixture just turns a bit of blue litmus paper
a red tinge. Now take a glass rod and make of it a mop by tying a
small bunch of clean cotton wool over one end, using for the purpose
a bit of white cotton. Having thoroughly washed the print for _at
least_ ten minutes in running water, lay it face up on a sheet of
glass, and apply the above toning solution with the cotton wool mop.
Having got a tint or colour nearly what you want, but allowing for a
loss of red in fixing, wash off the toning solution and immerse the
print in:--
19. Washing soda 1 ounce.
Water 10 "
for three or four minutes, and then fix in the usual way in a ten
per cent. hypo bath.
Here are some platinum toning baths well recommended:--
20. Lactic acid 2 drams.
Water 12 ounces.
Pot. chloroplatinite 2 grains.
21. Citric acid 20 grains.
Water 10 ounces.
Table salt 20 grains.
Pot. chloroplatinite 2 grains.
22. Phosphoric acid 3 drams.
Water 10 ounces.
Pot. chloroplatinite 2 grains.
The chief points to bear in mind in platinum toning are: (1) that
the print must have practically all the free silver washed away
before toning. To this end it is a very good plan to dip each print
for a couple of minutes or so in a bath of table salt one ounce,
water ten ounces, and again rinse under the tap for a minute or
two.
(2) That the toning bath is acid, therefore one must either
neutralize this acidity by passing through an alkaline bath, such as
No. 19, or what perhaps is rather more convenient, though not quite
so desirable--_i.e._, using a fixing bath made distinctly alkaline.
The following proportions are recommended:--
23. Hypo 1 ounce.
Water 10 ounces.
Soda sulphite 1/2 ounce.
Washing soda 1/2 "
_Toning with Gold and Platinum._--A large number of experimenters
have tried to find out how to produce platinotype-like effects with
P.O.P. papers. Perhaps none of them have been completely successful.
The following procedure, however, seems to give the nearest approach
to that ideal.
The best results are obtained with a slightly matt-surfaced paper.
This should be printed a shade or two deeper than the print is
intended to appear finally. The print is well washed and then
_partly_ toned in a gold bath:--
24. Soda acetate 30 grains.
Borax 25 "
Water 10 ounces.
Gold chloride 1 grain.
It is then washed for a minute or so, and the toning continued in
the following bath.
25. Phosphoric acid 1 dram.
Water 5 ounces.
Pot. chloroplatinite 2 grains.
Wash for five minutes and fix in bath 23.
_Intensifying and Reducing P.O.P._--When the negative is obtainable
and printable it is _very_ much better, and altogether more
satisfactory to make a fresh print than to attempt to intensify or
reduce an unsatisfactory one.
Nevertheless, it sometimes happens that this course is not possible,
and the best has to be made from an unsatisfactory print.
If the print is only very lightly printed, and comes straight from
the printing frame, it is best to strengthen it by development (see
formula 17 _et seq._). If the print has been toned and fixed, etc.,
the following may be tried:--
26. Make a _saturated solution_ of mercury bichloride in cold water,
let it settle, and use only the quite clear supernatent liquid.
Immerse the print in this for 15 minutes, turning it from time to
time, and see that no air bells are clinging to either side. Wash
the print in running water for 15 minutes at least, and longer if
convenient. Then immerse it in a bath consisting of strong ammonia
one part, water ten or twelve parts. Again wash for five minutes
under the tap.
_Reducing P.O.P._--
27. Hypo 120 grains (120)
Uranium nitrate 4 "
Water 2 ounces.
The advocates of this solution claim for it that it can be used
either _before_ or _after_ toning with equal facility and advantage.
Prints must be well washed both before and after its use in any
case.
Another method, which is somewhat risky except in expert hands, is
as follows:--
28. Dissolve metal iodine in alcohol to a rich dark port wine
colour. Dilute a small quantity with cold water until the whole is a
pale sherry colour. Now prepare a one in ten solution of potassium
cyanide (_N.B.: a powerful poison_) and add this a _little_ at a
time until the pale yellow colour of the iodine solution is just
discharged.
The print may be immersed in this until sufficiently reduced, or it
may be applied locally with cotton wool mop (as described above
under platinum toning formula 18). The print must of course be
quickly washed just before the desired degree of reduction has been
produced. This solution acts somewhat quickly when once the action
begins, and therefore it is well to deal with prints one at a time.
DEFECTS, ETC.
_Red-orange_ patches are usually due to touching the gelatine
surface with dirty fingers, etc. These places, being somewhat
greasy, repel the various fluids and cause uneven action of the
developing, toning, etc.
_Brown Stains_ are also often produced in the same way. They may
_sometimes_ be removed by the application of a saturated solution of
alum. If this fails one may try "chloride of lime" ("bleaching
powder") one part in twenty parts of hot water. Allow to stand until
cold and apply with cotton wool mop.
_Yellow Stains_ may sometimes be removed by a dilute solution of
potassium cyanide (poison) of strength one part cyanide in fifty
parts water. (Yellow stains usually indicate hypo splashes.)
_General Fog from Age._--This sometimes may be considerably reduced
by giving the prints the bath of: Soda sulphite (one in fifteen)
_before_ toning, but well washing after this bath and before toning.
_Very Slow Toning_ generally points to the fact that the toning bath
is too cold, or that it has been spoilt by a small quantity of hypo
or developer, or that it does not contain sufficient gold.
_Uneven Toning, i.e._, blue edges, generally points to a bath too
strong in gold, or that there are too many prints in the bath at
once, so that the edges are getting more of the metal than the
central parts, or it may arise from prints sticking together or to
the bottom of the dish.
_Blue-Grey Tones_ indicate too long a time in the toning bath, or a
bath too strong in gold.
_Red-Yellow Tones_ arise from just the opposite state of affairs.
_Pinking_ of the high-lights points to the bath being too weak or
becoming worked out.
_Double Toning_, _i.e._, the print shewing different colours, points
to insufficient washing or uneven action of the toning bath, _i.e._,
not keeping the prints moving, or too slow toning, or that the
toning bath does not suit the brand of paper.
_Blisters_ are usually due either to using a hypo fixing bath too
strong, or passing the print from one solution to another of a
markedly different temperature. Hence the importance of dissolving
the hypo either in tepid water or some time before use. The best
all-round temperature for working this process is between the limits
of 60° and 65° F.
_Tinting P.O.P._--The colours to be used may be the usual moist
water colours by some good maker, or solutions of aniline colours.
These latter may usually be dissolved in water and applied in thin
washes. The surface of the print should be rubbed as little as
possible. If water colours are to be used it will be found helpful
to prepare the surface of the print with one or other of the
following preparations.
29. White (bleached) lac. 1 part
Alcohol 12--15 parts
Apply evenly and quickly with a spray diffuser or with a broad soft
brush, and let the print become _nearly_ dry before applying the
colours.
30. The white of an egg in twenty ounces of water. Shake well, then
add ammonia drop by drop until the mixture just very faintly smells
of it. Filter and brush over the surface of the print. In mixing the
water colours also use this albumen solution in place of water.
_Advantages of P.O.P._--As compared with ordinary albumenized silver
paper the P.O.P. class has the advantage of giving more detail with
marked transparency in the shadows. The operations are more flexible
and the results are as permanent, if not more so, than those on
albumen paper. The paper keeps in good condition for a longer time.
The negative giving the best results with P.O.P. is one having
delicacy rather than vigour, _i.e._, a long scale of gradation of
delicate steps is well rendered. Printing takes place quicker with
P.O.P. than with albumen papers. The cost of paper and materials is
much about the same in both instances.
_Notes._--In the glazed variety of paper the smooth shiny surface is
the sensitive one, and, of course, goes next the negative in the
printing frame. In the matt paper the sensitive side may generally
be known by its tendency to curl inward, _i.e._, the concave or
hollow side is the printing side.
Formalin may be used in place of alum for hardening the gelatine. Of
the usual 40 per cent. solution of formalin take one ounce and
dilute with ten or twelve ounces of water.
Dark spots or specks are frequently due to metallic dust either from
the fingers or in the water. Mounts having sham gold edges or bronze
powders should be banished from the dark-room. Dry "pyro" floating
in the air may also account for spots.
_Rev. F. C. Lambert, M.A._
[Illustration: UNLOADING. A. M. MORRISON.]
_Platinotype Printing._
[Illustration]
Amongst the various printing processes in common use amongst
photographers, platinotype is unique in several respects.
Printing is conducted by daylight in precisely the same manner as
silver printing, but the action of light only suffices to make the
image partially visible. In this respect, platinotype stands, as it
were, midway between what are familiarly termed "print-out"
processes--that is, those in which the image is made completely
visible by daylight, and those in which the action of light is
latent or invisible, such as bromide paper and in the carbon
process.
The distinctive character of the platinotype print, with which,
probably, everyone is so familiar that a platinotype effect almost
amounts to a generic term, is not so much essential to the process,
but has been largely determined by the different kind of papers and
the preparation of those adopted by the manufacturers of platinotype
printing papers.
In the first place, the platinotype print is before anything a matt
surface print, and possesses a certain kind of texture or surface
which gives the finished print an appearance similar to a pencil
drawing or an engraving; an appearance largely assisted by the
characteristic colour of the platinum image, which is black.
The invention and production of platinotype paper is due to Mr.
Willis and the Platinotype Company, and although subsequently there
have been both English and foreign imitators, we may safely confine
our attention to those papers made and supplied by the Platinotype
Company.
As, however, the purpose of this article is to furnish the beginner
with simple working instructions, rather than to describe the
principles of the process, we will at once proceed to say how a
platinotype print is made.
To begin with, platinotype printing is divided into cold-bath
process and hot-bath process. Of the latter we shall speak later on,
but for the present, as being most suitable for the amateur and
beginner, we will consider the cold-bath method. The reason for this
division and the meaning of the name will be abundantly evident
presently.
We first of all procure a tin of paper of the quality marked AA. The
paper is put up in tin cylinders containing twenty-four pieces of
either 1/4-plate or 1/2-plate sizes, or less for larger sizes. It
may, if preferred, be obtained in full-size sheets 20 × 26 inches.
We have now to bear in mind that the paper is sensitive to daylight
to a slightly greater degree than are the silver print-out papers,
and hence, whilst handling the paper, placing it in the printing
frames, or what not, we need to be a little more careful as to how
near the window we bring the paper. At the side of the room furthest
from the window, or with an intervening screen between the paper and
the window, or yet again, with the blind drawn down, we shall be
quite safe in opening our tin of paper and inspecting it.
On removing the lid of the tin we find a false top or cover
hermetically sealing it, which has to be cut through in the manner
becoming customary with various tinned foods and comestibles.
We then find that the paper within is yellow on one side which is
the sensitive side. Within the roll of papers at the bottom of the
tin we shall find a hard irregular lump of some substance wrapped
round with cotton wool. Keep this in the tin and now note its use
from the following:--Platinotype paper is highly susceptible to
moisture and deteriorates under its influence. The air we breathe,
and therefore the air enclosed within the tin case or any other
vessel contains a large amount of moisture, and this moisture would
be taken up by the platinotype paper to its own detriment. The
presence of water or moisture in the atmosphere or in things we
handle, although quite unperceived by us, would be discoverable by
the platinum salts on the paper, which would thus become unfit for
use, hence the only way of preserving it is by placing in the tin
containing the paper some chemical which is even more susceptible to
moisture than platinotype paper. Such a body is calcium chloride,
and this it is which we find wrapped in cotton wool in each tin tube
of paper, or to speak more accurately it is asbestos prepared in a
solution of calcium chloride. So long as that little lump remains
dry and hard we may be quite sure that it has left no moisture in
the air around it for the platinotype paper, and it will go on
drinking it up until it becomes softened by saturation, when it must
be removed and a fresh piece substituted, or it may be restored to
its former condition by drying it on a red-hot shovel, the asbestos
remaining unconsumed.
Whilst perhaps in after practice we may find it possible to relax
our precautions against damp, yet at the outset the necessity of the
utmost caution being observed cannot be too strongly insisted upon.
Out of a very large number of prints representing the beginner's
first attempts at platinotype, by far the greatest number of
failures are due to damp, and this, probably, for want of conception
of the danger to which the paper is exposed. Remember then that
where there is ordinary air there is also abundant moisture, and as
no tin box with a movable lid is air-tight, neither is it
moisture-proof, but in the case of our tin of platinotype paper when
once opened will go on admitting moisture which the calcium chloride
will take up until it can take no more.
After having cut through the inner sealed top of the tin, close up
the little hole in the outer lid where the cutting point is with
sealing wax, next cover the mouth of the tube with a piece of waxed
paper or tinfoil, shut the lid down on to this, and then cover the
junction of the lid with a broad indiarubber band. In this way damp
may be prevented from gaining access to the inside of the tube to a
great extent.
Specially constructed tubes are made which close with an air-tight
stopper and have a false bottom with a perforated partition in which
the calcium chloride may be kept. Such a "calcium-tube," as it is
called, if not an absolute necessity, is a very desirable
acquisition.
If you now take the negative to be printed from and hold it near the
fire or a spirit lamp, it will on becoming warm give off
perceptible moisture, thus showing that it was distinctly damp
before. The negative, therefore, should be dried before being
brought into contact with the platinotype paper.
[Illustration: STREONSALCH. W.J. WARREN.]
The wood printing frame itself, if it has been used for printing in
the open air, should be placed in an oven or held near the fire to
thoroughly dry it.
Having placed the negative and the platinotype paper in the frame in
the ordinary manner, there should next be placed at the back of the
paper a thin sheet of waterproof cloth, vulcanized rubber of the
proper size and thickness being sold for the purpose; this will
prevent damp from penetrating to the paper from the back of the
frame. The frame may now be closed and placed in the light for
printing, and even having taken all these elaborate precautions
against damp it would not be advisable to print out of doors except
in dry weather, nor should the paper be left in the frame longer
than need be, but if it is not proposed to finish the print off at
once, it should be returned as soon as convenient to the security of
the calcium tube.
GENERAL OUTLINE OF THE PROCESS.
Platinotype paper is ordinarily only available for daylight
printing, though the Platinotype Company have introduced a lamp of
special construction and great power, by the use of which daylight
may be dispensed with, and electric light, should it be available,
may be used.
As has been already said, platinotype paper is rather more sensitive
to light than silver paper, and hence takes proportionately less
time to print.
The duration of the exposure to light constitutes the only real
difficulty in platinotype printing, and whilst just at first it may
result in the beginner's meeting with much disappointment, yet
probably, with a little care and watchfulness the trouble will be
surmounted, and sufficient experience gained to secure fairly
uniform success thereafter, before even the first tube of paper has
been used.
The printed image shows on the yellow ground of the sensitized side
as a faint grey, the darkest portions assuming an orange-grey tint,
whilst the lighter parts remain all but invisible.
A little practice will enable one to judge the right depth, that is
to say, how visible the image should be before printing is to be
stopped, but as a rough guide to commence with it may be said that
printing is complete when the image is about half as deep as we
should expect it to be if it were a "print-out" process.
As we shall have occasion to return to the question of printing
presently, we may now pass to the next step in the process.
In twenty-five ounces of hot water dissolve half a pound of best
neutral oxalate of potash, and keep this in a stoppered bottle as
stock solution. What is known as _neutral_ oxalate should be used,
and in order to ensure having a suitable salt it had better be
obtained from a recognised photographic chemist or dealer.
As the above solution becomes cool, a good deal of the oxalate will
probably settle at the bottom in the form of solid crystals; of
these no notice need be taken, for as long as there are undissolved
crystals at the bottom of the bottle we know we have a saturated
solution.
We shall now require a dish of porcelain or enamelled iron, and if
we choose the latter great care must be taken to see that the enamel
is not cracked or blistered, as it will have an injurious effect if
the oxalate of potash solution obtain access to the iron under the
enamel.
As it will be convenient to be able to alter the temperature of the
solution when in this dish at will, a spirit lamp or stove or a
small gas-stove will be a useful, if not an essential addition. Over
such heating apparatus the dish should be supported on an iron
tripod, or by any extemporized substitute.
If a porcelain dish be used, a thin sheet of iron should be placed
first on the tripod stand, and then three or four scraps of iron,
large common iron nails will serve very well, and on these the
porcelain dish is allowed to rest so that it does not come into
direct contact with the iron plate.
The purpose of this is to save the dish from cracking, moreover the
iron plate becomes hot, and retaining a good deal of heat serves as
a kind of accumulator which goes far to maintain the dish and the
contained solution at a uniform temperature for at least a short
time. Even better than this arrangement will be an iron dish filled
with clean dry sand, the porcelain dish to rest on the sand which
retains much heat.
If an enamelled iron dish be employed, these precautions are not so
necessary, though they may still be used with advantage.
Next we shall require another dish or similar vessel into which we
pour a weak solution of hydrochloric acid, the usual proportions
being:--
Water 70 parts
Pure hydrochloric acid 1 part
This constitutes the whole of the very simple apparatus needed, and
we may now proceed to develop our print, which as already described
is exposed to light in a printing frame in the usual manner until
the image appears rather less than half-printed.
DEVELOPMENT OF THE PRINT.
If convenient it would be an advantage to have the above-mentioned
apparatus set up close to the window or other situation where the
printing is actually carried on in order that each print may be
developed and finished off forthwith,; the reason for this will, I
think, appear as we proceed.
Development--that is, the changing of the print from the partially
visible condition to its full degree of intensity--is practically
instantaneous. The image does not gradually attain its maximum
strength as in a negative or bromide print, but does so within a few
seconds of its coming into contact with the oxalate of potash
solution.
[Illustration: Fig. 1.]
Having put into the dish on the tripod stand sufficient of the
saturated solution of oxalate of potash to cover the bottom of the
dish to the depth of half an inch or an inch, we light the lamp or
stove and bring the solution up to a temperature of about 70°
Fahrenheit. This may be tested with a thermometer or may very well
be guessed by touch; we merely require the solution quite warm, but
not so hot as to cause the slightest inconvenience if the fingers
are placed therein. This will be a sufficiently accurate guide as to
temperature.
In case any dust or scum should have accumulated on the surface of
the bath, wipe the surface of the solution with a piece of clean
paper, and now take the first print to be developed in both hands,
giving it a decided curl, or roll it round into a cylinder
_sensitive side out_, so that it naturally takes a curled-up form
(Fig. 1). We now take the print to the dish containing the oxalate
solution without previous washing and without exposing the paper to
the influence of light or moisture, and lowering the edge of the
paper held in the left hand, sensitive side downwards, until it
touches the fluid quickly and smoothly bring the rest of the print
down until the right-hand end finally reaches the solution, then
give it a sliding sort of shake in order to set free any bubbles of
air which may be imprisoned under the paper, and then on raising the
paper again after five to ten seconds, the image will be found to
have come out to the full degree of visibility, which the amount of
exposure had paved the way for.
The paper may be returned to the oxalate bath for a minute or two
longer if it be thought desirable, though only in the case of a very
cold bath is any effect produced on the print by the oxalate after
the first few seconds. The print is then passed _direct_ to the
hydrochloric acid bath, which should be ready in a dish close at
hand, and the print is now practically finished.
Before placing the print in the acid bath it may be noticed that the
portions of the print not affected by light still remain yellow, and
this yellowness the acid bath removes almost at once.
In order to effectually remove the yellow surface (which is the
unacted-upon sensitive salts and hence upon their removal the
permanence of the print depends) three successive applications of
the acid bath should be resorted to, the prints remaining for 5 to
10 minutes in each, and then finally washed in running water for a
quarter-of-an-hour, dried between blotting paper or in any other
manner preferred, and the platinotype print is finished and ready
for mounting.
It should be seen from the foregoing general outline of the process
that for directness, simplicity, and for the short time in which a
finished print may be produced that platinotype stands alone amongst
printing methods.
There are, however, some points needing careful consideration at
each stage of the print's production, and to these we may now pay
attention.
PRACTICAL CONSIDERATIONS AS REGARDS EXPOSURE.
As has already been stated right exposure constitutes the
crux of the whole process; this once mastered the rest of the
performance--development, clearing in acid and washing--is so simple
that the chance of failure is remote.
Hence the greater need of paying especial attention to the question
of exposure or printing.
Obviously, the duration of time of exposure cannot be fixed, not
even to the extent it can be in bromide printing or any other method
of printing with artificial light which may be a definite and
permanent quantity.
The variable quality of the daylight and the density of the negative
are both fluctuating factors in the calculation and hence some means
may advisedly be resorted to for acquiring a sort of exposure index
suitable for each individual negative and every variety of light.
First let it be noted that even with very great over-exposure the
image will not become wholly visible, whilst to the inexperienced
eye but little change takes place in the appearance of the printed
image after the correct exposure has been reached.
If then the print has been over-exposed, the fact is not made
evident until the print is subjected to the influence of the oxalate
developing bath.
To start platinotype work trusting to chance or good fortune to
secure for us good results, means that our whole course will be one
of uncertainty and filled with exasperating disappointments to say
nothing of the amount of paper and material which is certain to be
wasted in unsuccessful efforts.
The reader will probably have learned something of this from his
past experiences of negative exposure, the difficulties of which he
has by now, we may hope, overcome by careful and patient study, or
else if he is not even now undergoing this stage of learning he is
the victim of endless mistakes, every plate exposed is a shot in the
dark with no certainty attending any one of them.
Exposure, however, in platinotype is not so difficult a matter as
that of a dry plate, and the correct exposure with any particular
negative once ascertained, every subsequent print from the same
negative can, by simple mechanical means, be made with the certainty
of its being _an exact facsimile_ of the others.
PRINTING WITH AN ACTINOMETER.
Several kinds of Actinometers are made for sale, the purpose of
which is either to indicate the right exposure of a plate in the
camera or to tell the duration of exposure for papers such as
platinotype or carbon, the image on which is invisible, or nearly
so.
A simple, yet thoroughly efficient meter may be made as
follows:--Cut some fine tissue paper or _papier minéral_ into strips
about a quarter of an inch wide and attach one to a piece of clean
glass 4-1/4 × 3-1/4 with fresh starch or other colourless mountant.
Upon this first strip and exactly over it place a second, but bring
it to within a quarter of an inch of the end of the first, next
place a third strip in like manner a quarter of an inch short of the
second strip, and so on until some seven or eight strips have been
fixed. The combination will now be somewhat as the following drawing
(Fig. 2), thus forming a tissue band which at each quarter-inch is
one thickness more opaque.
[Illustration: Fig. 2.]
In the centre of each strip or increased thickness, paint with
opaque colour, black or red, a letter or figure as in (Fig. 3). On
the back or other side of the glass to which these strips are
attached, paint over or cover with opaque paper all except the space
covered by the strips. Now place the whole in an ordinary 1/4-plate
printing frame, with the paper strips inside, next adjust a piece of
silver paper, albumenized, or gelatine chloride precisely as though
printing from a negative. Close the back and we then have a
thoroughly efficient actinometer.
[Illustration: Fig. 3.]
We now put out our first piece of platinotype paper to print, and
alongside it so as to receive the exact same amount of light, we
place our actinometer.
The first print must admittedly be guess-work.
After an interval of time, which may vary from say fifteen minutes
to an hour according to the amount of light, we will withdraw the
frame containing the platinotype print, and _simultaneously turn the
actinometer over with its face down_, thus stopping its printing
whilst examining the platinotype.
Retiring from the light we examine the progress of printing
precisely as in silver printing, and we shall probably find that the
image on the negative is now faintly visible on the platinotype
paper, impressed in a sort of warm grey colour.
If the darkest portions are of about the tint which we might produce
by shading with an H pencil on a piece of primrose yellow or pale
buff paper, we may reckon that the print has been sufficiently
exposed.
Now refer to the actinometer and see what has taken place on the
silver paper which we put into it. Probably while the platinotype
paper has been reaching the required depth of printing, the silver
paper has also registered the image of the strips of paper, and has
become printed through up to the fourth or fifth step of the tissue
strips, showing on each strip its letter in white. Make a note of
the highest letter visible and proceed to develop the platinotype
print. If upon development the print is weak and grey, lacking depth
or intensity in the deepest shadows, and having blank and detailless
whites for the higher tones, we may reckon that our print is
under-exposed. The letter visible then, _with that particular
negative_ is not sufficient. We then shift the paper in the
actinometer so as to get a fresh portion under the tissue strips, or
we substitute a new piece. We refill the printing frame and print
again until the actinometer registers one, two, or three more steps
and letters, and then try again. If, however, in the first case the
platinotype print upon development gives a heavy dark print, with
the details in shadows blocked up, and the high-lights grey, the
whole possessing an overdone appearance, then in our second attempt
we shall stop printing when the actinometer records some one or two
letters less. But we may be more fortunate in our first attempt, and
the print may be about right. In that case we mark on that negative
in some way the tint or step or letter in the actinometer at which
we arrested action, and henceforth, no matter the time of year, hour
of the day, or latitude, that negative will give a similar print if
stopped in accordance with that memorandum which it bears.
If, however, we do not hit the right exposure the first time, we are
pretty certain to do so the second, or at the most the third time,
and having done so, we have not only an infallible guide for all
subsequent prints from that same negative, but we have also some
sort of index to base our calculations on for other negatives. Thus
if we at once proceed to print from another negative, that is,
before any considerable alteration takes place in the light, we may
by comparing the negatives at least estimate what will probably be
the second negative's printing letter or step on the actinometer.
Sooner or later every negative (especially those from which we
anticipate wanting subsequent prints) should bear either on the
negative itself, or else in a carefully kept register or note book
its correct printing letter.
Although this may seem a rather laborious practice, it is not so in
reality, and so great is its educational power that I anticipate
that after the first dozen or so negatives we shall almost dispense
with the actinometer altogether, having by then trained the eye to
tell when a print is finished merely by the appearance of the
half-visible image. Do not let this prospect, however, tempt the
beginner to dispense with this valuable help at first, for to the
inexperienced eye the appearance of the platinotype image is very
deceptive, and having under-exposed the first print, it will not be
safe to judge the extra printing of the next print only by the eye;
the beginner is nearly certain to err, and the eye must not be
trusted until it has had considerable training.
After having had some considerable and varied experience in
platinotype printing, one feels no little regret that an operation
which has become so simple cannot be laid before a beginner in a
more precise and definite manner, and I can only assure my reader
that in a very little while what may now look like a very serious
business, only surmountable by long and serious practice, will
become a sort of intuitive faculty, and just as one feels after a
little practice the precise amount of pressure which one should use
when the fingers are placed on the notes of the piano, so just the
right _visible_ depth of print required to give a developed print of
such and such intensity comes to be a matter of instinct.
It may here be stated that paper which has been affected by damp
gives a slightly less visible image than dry paper. But moisture
alone without oxalate will effect partial development, and if the
time of exposure to light be so greatly prolonged, that despite all
precautions moisture obtains access to the print during exposure,
this may, as it were, start a kind of local development whilst the
paper is still in the frame and printing, so that on looking at the
print to watch its progress some of the deeper shadows may have
sprung quite suddenly into a deep blackish-grey colour. In many
cases this will quite spoil the finished result, whilst in others no
harm seems to be done when the print is ultimately developed.
Remembering that the high-lights and indeed some of the lighter
tints of the print are quite invisible until after development,
care should be taken to look at the paper only in decidedly subdued
light, or better still, artificial light, because the injury which
is being done by even a short exposure to actinic light is not made
manifest until after development, and as most of us know how soon a
piece of silver paper will discolour in even moderately faint
daylight, we should be additionally cautious with platinotype paper
which is from twice to three times as sensitive to light.
[Illustration: Fig. 4.]
SOME POINTS TO BE CONSIDERED WITH REGARD TO DEVELOPMENT.
To avoid confusion it will be well to repeat here that at present we
are only considering the practice of what is known as the cold-bath
paper. This term is applied only in a comparative sense. The older
hot-bath process requires the developing bath to be raised to a
temperature of about 170° F., whereas the best temperature for the
cold process is about 70° F. or even less; nevertheless, the
cold-bath paper _may_ be developed in an oxalate bath of 170° or
even hotter, so also it may be developed on a solution which is
quite cold. The result of altering the temperature is two-fold and
may be stated thus:--_The colder the bath_, the _colder_ the colour,
that is, the _bluer_ the greys and blacks, also development is
slower and takes longer, and the contrasts harder. _The hotter the
bath_ the warmer or browner the colour of the print; the more sudden
the development and the greater the amount of half-tone and
consequent softer contrasts.
With these maxims in mind some amount of control may be exercised
over the prints produced, especially as regards arresting
development at any point desired if a cold developer be used, but in
such case the print must be instantly removed to and plunged into
the acid bath, until which immersion development continues, even
after the print has been removed from the bath.
Development, as a general rule, should be conducted in feeble
daylight or artificial light.
Development need not take place immediately, but at some subsequent
time, provided the prints be meanwhile stored in a calcium tube and
in every way rigorously protected from damp.
The proportions which I have given for the oxalate of potash bath
represent the standard developer as given by the makers of the paper
for the hot-bath papers, and they recommend that this be diluted to
about half strength for cold-bath papers. Personally, I use it at
full strength for the cold process, and see no reason for diluting
it.
It may be said that such a course is calculated to give strong,
vigorous prints, for generally speaking, the stronger the bath, the
stronger the contrasts of the print. The difference, however,
produced by altering the strength of the bath is not very great.
There are two alternatives to the oxalate of potash developer, both
possessing certain, if not very strongly marked characteristics. The
first of these is known as the "D" salts. These are sold in tins by
the Platinotype Company, and consist of a loose admixture of certain
salts, and hence it is essential that the entire contents of a
half-pound tin be dissolved at once and kept thus as a stock
solution.
The proportions to be used are as follows: Dissolve 1/2 lb. of D
salts in 50 ozs. water, and then take equal portions of this
solution and water, in other words, dilute it to half-strength.
The "D" salts are said to give colder colours and more half-tone,
but the colour derived from development on the first-named oxalate
bath may be made colder by adding to 20 parts of developer 1 part of
a saturated solution of oxalic acid, in like manner slightly warmer
colour may be obtained if the oxalate bath be made alkaline by the
addition of carbonate of potash, but only just enough should be
added to turn a red litmus test paper blue.
If prints developed on D salts should appear mealy or granulated,
the bath should be strengthened or used at the full strength of the
stock solution (salts 1/2 lb. to water 50 oz.).
Another developer, the effect of which is to minimize half-tone and
increase the vigour of the contrasts, and so give very brilliant and
even hard blacks and whites, is as follows:
Oxalate of potash 16 ozs.
Phosphate of potash 4 ozs.
Sulphate of potash 1/2 oz.
Water 120 ozs.
This should be made with hot water, and to get the full advantage of
its contrast-giving powers, used quite cold. Development will then
probably take one or two minutes, but can be arrested sooner when
the desired effect is attained.
It may now be as well to enumerate and describe the various kinds of
platinotype paper obtainable, and whilst the general treatment of
them all is the same as described in the foregoing, some special
recommendations may be made in each case.
The papers for the Cold-Bath process are two called respectively AA
and CC. AA is a smooth surface paper and is the kind usually
employed for portraiture and general small work. CC is a heavier,
stronger paper with a surface similar to stout cartridge or drawing
paper. For pictorial work and for landscapes, also for large
portraits or heads this paper is eminently suitable.
Next we have the papers for Hot-Bath process, to be presently
described. These are firstly A and C, both precisely the same in
character as the AA and CC just referred to, but intended to be
developed in a bath at high temperature. These four kinds of paper
all yield a picture of the normal platinotype black colour, the
black tending to cooler or warmer tints according to slight
modifications of treatment, but it is also possible to produce a
platinotype print of a rich sepia brown by using the papers S and
RS--these both in substance and character corresponding with AA or A
and CC or C respectively. Thus we have a thin smooth and a thick
rough paper for each Cold bath, Hot bath, and for Sepia printing.
DEVELOPMENT OF HOT-BATH AND SEPIA PAPERS.
With the Hot-Bath papers perhaps the precautions against damp should
be rather more stringent than for Cold-Bath papers, certainly they
may not be relaxed, and in the sepia papers, S and RS, there seems
to be even greater susceptibility still, but for this, printing and
development are performed precisely as already described, but the
temperature of the oxalate bath should not be less than 150° to
170°, whilst in some cases it may be convenient to raise it still
higher. The oxalate solution should, moreover, always be at full
strength, namely, 1/2 lb. in 25 ozs. of water or thereabouts, a much
more diluted bath will result in granular prints.
As a general rule the colour of A and C prints is a rather browner
black than their cold-bath equivalents--AA and CC--with also rather
softer contrasts.
Development takes place in shorter time than with cold-bath papers,
and is indeed so instantaneous that any control is next to
impossible. On this account, rather more dexterity will be required
in development, that is to say, between the time that one end of the
print touches the developer and the rest of the print is brought
into contact with it, the shortest possible time should elapse.
There must be no hesitation, the whole surface must be brought down
gradually but swiftly, and accompanied by a sliding movement in
order to squeeze out or wipe out any air bubbles which might cling
to the surface of the paper. If this be not done evenly and
continuously, it is more than likely that there will be marks of
unequal development on the surface.
[Illustration: Fig. 5.]
It is no uncommon thing for the tyro to let the print hover over the
bath before giving it its plunge in the hot solution, but in so
doing it should be remembered that he is submitting it to the direct
action of the steam which the bath is giving off, and so exposing it
to damp.
Whilst with prints of 1/2-plate size and under it may be sufficient
to hold the print by one corner and wipe it across the surface of
the solution, pressing it down with the fingers of the other hand,
with larger sizes it will be well to cultivate a little trick in
manipulation, and the accompanying figure may perhaps be suggestive
(Fig. 5), in which it will be seen the left hand is bringing one
end of the print into contact with the bath, whilst the right hand
holds the opposite end above and well back, and the left hand will
next be moved in the direction of the arrow, drawing the print with
it along the surface of the bath, the right hand following but
simultaneously lowering the whole of the print--thus the solution
attacks the print smoothly and continuously, whilst the air is
pressed out in the opposite direction. Instantly the entire print is
floating on the bath it should be moved about a little, as a further
means of disengaging any air bubbles.
As far as possible, prevent the developer from flowing over the back
of the print, but this will be a far less evil than not bringing the
whole printed surface immediately and at one stroke on to the
developer. The print is next passed direct and without intermediate
washing into the hydrochloric acid bath, as already described.
The sepia papers, S and RS, are both hot-bath papers, and no special
instructions need to be given as regards development, except that to
get the full benefit of the sepia tint and secure a fine rich bright
colour, the Special Sepia Solution prepared and supplied by the
Platinotype Company should be employed in the developer.
Of this, one or two drams should be added to each ounce of oxalate
bath, either before heating it in the dish or afterwards and just
before floating the prints. In the latter case stir the whole so as
to get it equally mixed, and wipe the surface to remove any scum.
A good substitute for the bath as above prepared for sepia prints
may be made by adding one part of saturated solution of oxalic acid
to each ten parts of oxalate of potash solution.
The Sepia papers are rather more sensitive to light than the Black
papers, and hence all operations should be conducted in very subdued
daylight, a precaution even extending to the first acid bath.
The bath containing the special solution should be used for sepia
prints only, and when done with kept in a separate bottle for future
use, but the bottle must be kept from the light, and the sediment
which will fall should be left undisturbed at the bottom of the
bottle or filtered out, and the dish used for sepia development
should be well washed before using it for black prints.
Opinions seem to differ as to the wisdom of keeping old developing
baths, but as far as my own experience goes I use the oxalate
solution for black prints again and again, taking no heed of its
discoloured condition.
After developing, the bath is poured into the stock bottle, and so
long as undissolved crystals remain at the bottom of the bottle hot
water may be added from time to time to make up the loss occasioned
by spilling and waste, thus the stock solution is always a
combination of old and freshly-dissolved oxalate, and I have had one
large jar of solution thus in very frequent use for over twelve
months, a greenish-black encrustation gradually accumulating at the
bottom without detriment.
CONCERNING THE HYDROCHLORIC CLEARING OR FIXING BATH.
Little needs to be said as to the Hydrochloric Acid bath into which
the prints are passed immediately after development. The purpose of
the acid bath is to dissolve out the sensitive salts which have been
unaffected by light and which are still light-sensitive, the removal
of these making the paper white and clean. Thus the acid bath is
both fixing and clearing in its action.
Into the first acid bath the prints will carry a good deal of the
oxalate solution in which they have been developed, and it therefore
soon becomes very much discoloured, wherefore after a lapse of about
five minutes the print should be removed to a second acid bath of
the same strength as the first (pure hydrochloric acid 1 part, water
70 parts) and after five or ten minutes into a third.
After the prints (many may be done at the same time) have been in
the third acid for five minutes, the bath should be examined, and if
it is quite colourless, that is if the prints have not discoloured
it at all, we may rest satisfied that clearing and fixation are
complete, but if not, yet another acid bath should be given.
Whilst five or ten minutes in each acid bath is long enough,
probably no harm to the print itself, yet no good, will follow a
longer immersion. There may, however, be a danger of softening or
rotting the paper, a danger which is increased should the bath be
made stronger in acid.
If a number of prints are being made, or if numerous dishes for acid
constitute a difficulty or inconvenience, we may modify procedure as
follows:--
Make up the first acid bath to about half the prescribed strength,
say hydrochloric acid one part to water 120 to 140 parts. Into this
each print may be flung as soon as developed, until the entire batch
is thus far finished. In this weak acid bath the prints will take no
harm if left for several hours, when an acid bath (one to seventy)
of full strength having been prepared, the first weak solution may
be poured off and the fresh poured on. In this the prints should be
separately turned over, so that each receives thorough treatment,
when the second bath may be thrown away and a third substituted. One
dish thus serves for the whole series of acid baths.
If adopting this course, it will be safer not to mix sepia and
ordinary black prints in the same _first_ acid bath, after which,
however, they may be treated altogether.
Sufficient washing to rid the paper of acid is all that is required
to complete operations; but acid does not cling to the print as does
hypo, moreover, we have not an absorbent gelatine surface to deal
with, so that if prints were dealt with individually and washed by
hand, probably a few minutes sluicing under a tap would suffice, but
in a properly constructed print-washer, or even a large dish, twenty
minutes to half-an-hour should be ample. If any doubt is felt, the
last washing water may be tested with blue litmus paper.
MODIFICATIONS IN DEVELOPMENT.
To impart a warmer and richer tone to prints on CC (cold-bath)
paper, the following slight modification may be resorted to, but it
must be regarded merely as an exception for definite purposes, being
in violation of the instructions and rules already laid down. It
consists of developing CC paper as though it were hot-bath paper,
using a bath of about 170° F and submitting it to the influence of
damp to a slight degree. This latter very heterodox course may be
effected by leaving the paper laid out all night in a room where
there has been no fire to dry the air, or by using paper which has
been kept for a week or so in its tube without calcium chloride and
without sealing the lid, or yet again, the print may be held over
the steam of the developer for a few minutes before developing it.
It must be remembered that in doing this we are taking liberties
with the process, and if poor, "muddy" prints result, we can only
blame ourselves, but as a rule this will not be the case, the effect
being rather to impart a slight creamy tone to the whites without
otherwise degrading their brilliance, whilst the use of a hot bath
gives the whole a distinctly brown-black image, which combined with
the cream tint of the high-lights has a very luminous and warm
effect.
Another method of development which must also be taken as an
exceptional one, only to be used in special cases to attain special
ends, is local development with a brush, using glycerine as a
medium.
As may have been seen from the foregoing descriptions, the
development of a platinotype print, even with a cold bath, is so
rapid that there is not a possibility of developing one portion more
than another, or if such could be done, still it would be done with
the certainty of leaving a mark where development had been stopped.
These difficulties, however, may be overcome by the use of
glycerine, the effect of which is to retard development to almost
any degree, and by its soft, viscid character to soften and blend
the line of demarcation where greater or less development ceased.
The method of applying it is as follows: On removing the print from
the frame it should be fastened to a board with pins, print side
upwards. Next pour on to the surface a small pool of _pure_
glycerine, and with the finger tip, a brush or soft pad, spread it
_evenly_ and thinly over the print. It must not be allowed to remain
on the surface in irregular patches of unequal depth, but after
spreading it had better be wiped with a fresh pad of cotton wool, so
as to remove any superfluous glycerine. Now have four small vessels
at hand, and into No. 1 place an ounce or two of the ordinary
oxalate developing solution, in No. 2 put equal parts of oxalate
solution and glycerine, in No. 3 one part oxalate solution and two
parts glycerine, and in No. 4 pure glycerine.
With a broad, soft hair brush apply the contents of No. 3 to the
less printed portions of the image and wait results. These portions
will presently begin to gain in depth and to slowly develop up, now
spread the No. 3 mixture to the rest of the print and apply the
contents of No. 2 to the portions first treated with No. 3. The most
obstinate parts may be touched with No. 1, plain oxalate solution,
whilst any spots which have come up too quickly may be promptly
arrested from further progress by the application of pure glycerine.
Here we have a method of developing up any one part, and restraining
or entirely stopping any other.
I do not think any good will be done by a more detailed description
of its working, even if there be anything more to tell. It is
essentially a method of development in which the individual worker
will invent modifications and dodges for himself, and when all is
said for it, it must be admitted only as a means of improving a
subject when ordinary procedure fails.
THE CHARACTER OF THE NEGATIVE FOR PLATINOTYPE.
In the earlier days of platinotype printing it was generally
insisted upon that the most suitable negatives were such as we
should describe as somewhat vigorous or "plucky." Whether it is that
some alteration has been made in the manufacture of the paper or
that taste as regards what constitutes a good print has changed, I
cannot say. Certain it is that in the experience of a good many, a
"plucky" negative is by no means essential to the production of a
good platinotype print.
The soft, delicate negatives, of which the best professional
portrait negatives are a good sample, yield the best possible
results, whilst with the CC paper, negatives so thin and delicate as
to be suitable for hardly any other printing process, give all that
can be wished for.
Much, of course, will depend on the kind of print desired and the
paper used, and here it may be remarked that from a given negative
the different kinds of platinotype paper give different results.
From a given negative the hot-bath papers yield the greatest amount
of half-tone, the hot development tending to yield flatter results.
Next comes the smooth, cold-bath paper, and finally as yielding the
maximum amount of vigour is the CC paper. Hence if we make our
negatives specially for our chosen printing process, a stronger
negative will be needed for S, RS, A and C than for the AA and CC,
whilst for the latter a negative distinctly erring on the side of
extreme thinness will be best.
If a negative gives prints which are too weak and flat for our
purpose, a great improvement may be effected by printing through
blue glass. If on the other hand the prints are too hard and harsh
in contrast, it is advisable to print through "signal" green glass.
TONING PLATINOTYPE PRINTS.
Several formula and methods have been published from time to time,
the object of which is to change the colour of the platinotype print
by subsequent staining or toning, and whilst by such methods
pleasing colours may sometimes be obtained, they possess an element
of uncertainty, and must not be too much relied upon. An exception
in this respect must, however, be made in the case of what is known
as Packham's method, the effect of which is to change the black
platinotype to a sepia brown, or a brown slightly tinged with green.
The necessary "tinctorial powder" must be obtained from Mr. Packham
or through a dealer. To prepare the bath a packet of this powder is
dissolved by boiling for three or four minutes in five fluid ounces
of water, to which when cold add one ounce methylated spirit. This
forms the stock solution and will keep for a long time if well
corked. For use add thirty or forty minims of the stock solution to
one pint of water, and in this steep the prints, turning them over
frequently. Toning may occupy several hours. To expedite matters,
the dilute solution should be made with water of 150° F., and the
bath maintained at this temperature as in the case of hot-bath
development. As soon as the desired tint is secured, remove the
prints and wash well in three changes of cold water.
Prints may be so treated at any time after they have been made.
Glycerine developed prints are not suitable. Prints must have been
very thoroughly washed, so as to free them from every trace of acid,
also thoroughly fixed in acid if they are to be "toned" by Packham's
method. If after "toning" and washing the whites of the print appear
to have suffered, the prints should be placed for five or ten
minutes in the following bath, which should be kept at a temperature
of 180° F.
Castille soap 40 grains
Bicarbonate of soda 80 grains
Water, hot (180° F.) 1 pint
This will clear the whites and intensify the colour generally.
Platinotypes may be toned to a red-brown by uranium nitrate, or to a
bluer colour with chloride of gold. They may also be intensified by
pyrogallic acid or hydroquinone, but as the purpose of this article
was merely to give simple working instructions for platinotype
printing for the beginner, he may defer the consideration of such
side issues until he has become _au fait_ in the production of a
good platinotype print.
_A. Horsley Hinton._
_Contact Printing on Bromide Paper._
[Illustration]
It is well to bear in mind at the outset that bromide paper is
extremely sensitive to light, almost as much so as is a rapid dry
plate. For this reason, it is obvious that it must not be carelessly
exposed to actinic light. All manipulations except the actual
printing must be conducted by red or yellow light, such as is
allowed to pass through glass of these colours.
For evenness of result, it is better to use a lantern than daylight,
because the fluctuation in intensity of the latter is very
misleading and liable to lead to failures through over or under
development.
The actual colour of the light, also, is of far more importance than
one would suppose: ruby light tends to give one the impression that
development is complete long before that is the actual case; it is
also somewhat more difficult to handle the paper satisfactorily by
this light than by a good yellow.
For these and other reasons I strongly recommend the use of yellow
light, a thoroughly safe one being given by gas or lamplight passing
through one sheet of yellow glass and one thickness of "canary
medium."
This light, while being absolutely safe, gives such perfect
illumination that it is as easy to control and estimate results as
it would be by ordinary unfiltered gaslight.
If a ruby glazed lantern is already in use for negative work, it can
readily be prepared for bromide printing by merely removing the ruby
glass and substituting the yellow and canary medium. With these
brief hints as to illumination, let us consider the entire process
in its various stages.
_Unpacking the Paper._--The sensitive paper is generally packed in
envelopes sufficiently opaque to protect it from the admission of
light. The packet must be opened in the dark-room from which _all_
light (even stray streaks beneath the door) is excluded, excepting
only that given by the yellow glazed lantern. The outer envelope
being carefully undone, an inner cover will be found and these
wrappers should be placed on a dry table while a sheet of the paper
is removed.
It is a good plan to have a "light-tight" box (obtainable from any
dealer) in which to put the paper after unpacking it; this prevents
loss of time and awkwardness of handling in having to replace the
paper in its wrappers each time a piece is withdrawn for use.
When several prints from one or more negatives are required, it is
an excellent thing to have two of these boxes, one for the unexposed
paper and one in which to put the prints as made until all are ready
for development.
_The Class of Negative._--Bromide paper gives us a great command
over results; in fact, so vast is the control we may exercise that
it is possible to secure good results from almost all classes of
negatives, from mere ghosts to those with density almost equal to
that of a brick wall. But there is, of course, a class of negative
that gives a good result with the least expenditure of skill, such a
one is generally known as of average density, having a full scale of
gradation with high-lights dense, yet not so opaque as to prevent
you seeing a window clearly defined when looking towards it
_through_ the densest parts of the film, such as the sky, for
instance. Another way to test the density is to put the negative,
film side down, on some large print on white paper, the large
letters should be just visible through the sky, but the smaller
print should not be readable.
That is the class of negative usually considered in Instructions for
Use, as an "average" negative.
_The Sensitive Side of the Paper._--A difficulty sometimes occurs in
telling which is the sensitive side of the paper: this may be easily
ascertained by the appearance of the edge, which turns slightly
inwards _towards_ the sensitive side. This is quite apparent to the
sense of touch as well as sight. Some people moisten their finger
and thumb and squeeze the paper and see which sticks (the sensitive
side), but that is a dirty method and quite unnecessary.
_Printing from the Negative._--Having unpacked the paper, after
making sure that all but the yellow (or ruby) light has been
excluded from the room, we are ready to print.
For this purpose, different workers favour different classes of
light: one prefers gaslight, another swears by magnesium ribbon, and
some even prefer the light of day.
Personally, I favour ordinary gaslight passed through a No. 5 Bray's
burner, because it is quite rapid enough for all practical purposes
and is perfectly under control and free from serious variation.
[Illustration: Fig. 1.]
The burner should be within easy reach of the worktable and should
be fitted with a byepass to obviate the necessity of continually
striking matches. Several years ago I had my bromide printing rooms
fitted with an excellent lantern of this class in which the byepass
was connected to two jets (one inside and the other outside the
lantern) in such a way as to turn down the white light with the same
movement that raised the coloured light, and _vice versa_. By this
means no gas was wasted and the simple action of pulling or pushing
a lever operated either light at will. By placing the same lever
"amidships," both jets were lowered to the point of invisibility and
could so remain for days at a time, yet always ready at a moment's
notice. The accompanying sketch (fig. 1) will give some idea of its
construction.
If the dark-room is small, and space is an object, the sink may be
fitted with a wooden cover and this may be used as a table for
printing the paper, but care must be observed to avoid the slightest
moisture upon it or satisfactory work is impossible and the
negatives may be ruined. In a large room, it is much better to have
an ordinary kitchen table removed some distance from the sink; with
this and a comfortable chair bromide printing is a very pleasant
occupation. The following sketch (fig. 2) will explain the
arrangement of the table, and it applies equally well to the movable
top of the sink.
[Illustration: Fig. 2.]
Supposing that some arrangement of this sort is devised, we must
unpack some bromide paper and put it in its box and then put a
negative of "average" density in an ordinary printing frame. On the
film side of the negative we must now place a sheet of bromide paper
with its sensitive side in contact, replace the back of the frame
and it is ready for exposure. Before exposing it, _make sure that
both boxes are shut_ or their contents will be ruined the moment the
white light is turned up.
Upon reference to the instructions that accompany each packet of
bromide paper, you will observe a certain number of seconds'
exposure is advised at a certain distance from the light; in the
case of the Barnet extra rapid paper the time is given as about
four seconds at a distance of eighteen inches.
When all is ready for exposure, place the printing frame upright
opposite the lantern at the mark indicating eighteen inches (see
fig. 2), note the time on the seconds hand of the clock and throw
the lever over for white light for four seconds and then reverse it.
Remove the paper and if many are likely to be required from that
negative, it would be well to develop the first print in order to
judge as to the accuracy of the exposure. If over or under-exposed,
the time must be reduced or lengthened as required. When the best
time and distance has been ascertained for a certain negative, mark
it with a narrow strip of paper bearing full particulars for future
guidance, such as: "4 sec., 18 in., No. 5 Bray;" in this way
absolute correctness of future exposures is assured. Of course, if
gas is not obtainable, magnesium ribbon may be used instead. In this
case the negative would be marked "1 inch (or more) ribbon, 3 ft.
distant," as the case may be.
_Using Masks and Discs._--Prints are sometimes required with an oval
(or square) centre and white margins: this is effected by
interposing a black mask of the desired size and shape (obtainable
from all dealers) between the negative and the sensitive paper. The
black paper prevents the passage of light and leaves white margins
to the print. If grey margins are required, a disc (to fit the mask)
is attached to a sheet of glass the same size as the negative and
arranged so that registration is easily effected; the print is first
made with a mask and is then placed in contact with the disc and
plain glass (the negative being removed from the frame), and again
exposed for a second to the light. If a black border is required the
exposure of the margin must be extended three or four seconds.
_Vignetting._--To vignette bromide prints, the printing frame must
be covered with a piece of cardboard in which a small hole (about
1-1/2 inches by 1 inch for a cabinet head and bust) is pierced. The
hole _must_ be covered with a sheet of white tissue paper which will
diffuse the light and cause it to travel without harsh lines beneath
the opening, and make the print with perfectly gradated edges. It is
sometimes an advantage to move the negative while printing
vignettes; but it is not absolutely essential if the hole in the
cardboard is not too large and if the card is removed some little
distance from the negative. If the card is too close to the
negative, the gradation will be abrupt and the vignette will not
look well.
_Cloud Printing._--This requires some care in order to avoid
harshness and sharply defined lines. If the sky of the negative
prints white, the addition of clouds from another negative is not
difficult; but if it is at all thin, the entire sky must be
carefully painted out with a deeply opaque pigment in order to make
it quite dense and unprintable.
As a bromide print cannot be examined while in progress: that is,
cannot be seen at all before development, careful registration is
desirable in order to prevent printing the clouds across the
landscape instead of above it. To do this an opaque mask should be
made thus: Make a print from the negative on P.O.P. and, without
fixing or toning it, cut it carefully in two parts following the
horizon line as nearly as possible, then expose to light, until
quite black, that part representing the landscape. Attach this to
the glass side of the cloud negative (with the paper side of the
P.O.P. in contact) and see that the bottom edge and the right corner
of the paper and glass (viewed from the glass side of the negative)
exactly coincide. To make use of this arrangement, you first make a
print from the landscape negative, making sure that the negative and
paper are firmly pressed against the bottom and left-hand side of
the printing frame when looking towards the film side of the
negative; mark the registered corner with lead pencil thus =L= in
order to prevent mistakes in the second printing.
To print the clouds, you put the negative in the frame and press it
well home to the left-hand corner and the base of frame (looking at
the film side, of course), and then put the print in contact with
the same precaution and replace the back. Now take a piece of brown
paper with one edge roughly torn in shape of the horizon line of the
mask and cover the entire negative on the glass side. Hold the
covered frame in your hands at a distance of (say) four feet from
the gas and turn on the white light. Directly the light is up, draw
the paper slowly downwards until the horizon line is just passed,
and then _immediately_ begin to slowly push it upwards towards the
top of the sky. Do this steadily and slowly for (say) four to six
seconds, according to the density of the cloud negative. With a good
thin cloud, four seconds should be quite enough, but you can easily
settle this point on developing the first print.
_Printing from Dense Negatives._--Dense negatives require much
longer exposures than those of "average" (or ideal) density. This
may often be prolonged to twice or three times the normal exposure
at the same distance. A yellow coloured negative increases the
exposure greatly, as much as ten to thirty times the normal
frequently being requisite to get a decent print. An over dense
negative that gives very harsh prints by other printing processes
can be made to yield prints of exquisite softness on bromide paper
by giving a full exposure at a _short_ distance from the gas.
[Illustration: CUPBOARD LOVE. T. LEE SYMS.]
_Printing from Thin Negatives._--Thin negatives on the other hand,
require quite different treatment. In order to get plucky prints
from very thin negatives, useless in other processes, we must give a
very brief exposure at some distance from the gas; and here it may
be well to note that removing the negative to a greater distance
from the light is equal to decreasing the actual time of exposure
and has other advantages in connection with thin negatives with
which theory does not seem to agree. To print from a very thin
negative, then, instead of four seconds at eighteen inches, let us
cover it with a sheet of tissue paper and give it four seconds at a
distance of three or four feet and note the result on development.
If it appears to be over-exposed, we may reduce the time of exposure
to three seconds at the same distance and modify the developer, as
will be explained later on.
_Development of Prints._--All my remarks in this article apply
equally to most commercial brands of bromide paper; but it is only
fair to state that they are particularly intended for that made by
the firm of manufacturers publishing this book. Development, and so
on, is very similar with all makes of paper, but most of my recent
experiments have been made on the "Barnet" matt surface bromide.
I shall presently describe the use of several well-known developers,
but it must be well understood that, whatever formula is adopted, a
preliminary soaking of the print before development must be done.
When we are about to develop a number of prints we must first soak
them in plain cold water until quite flaccid, otherwise the
application of the developer would cause the dry print to cockle and
curl, and the development would not be regular. This rule applies
equally in the case of one print only as when a hundred are ready
for development; a prolonged soaking in plain water having no ill
effect.
_The Iron Developer._--This is one of the developers most frequently
recommended for bromide work, but personally I never advise its use
(especially by a novice) because the use of the acid clearing bath,
which is an essential part of the process, is so frequent a cause of
disaster and yellow prints. The Barnet formula is as follows:--
A.
Potassium oxalate 1 lb.
Potassium bromide 5 grains
Hot water 48 ozs.
B.
Iron sulphate 1 lb.
Citric acid 4 drams.
Hot water 32 ozs.
To six ounces of A, add one ounce of B; this order of mixing must be
observed or a dense precipitate of ferrous oxalate will be formed.
Place one of the soaked prints face (which may be distinguished by
its "slippery" surface) upwards in a clean porcelain dish and pour
the developer over it as evenly as possible. With this developer,
the image comes up very rapidly, so that it is not advisable to try
and develop more than one at a time. If the first print of a batch
appears to be over-exposed, that is, if it flashes out instantly and
the high-lights become rapidly clouded, add to each ounce of mixed
developer from 10 to 30 drops of a ten per cent. solution of
potassium bromide which will act as a restrainer, retard
development, and keep the high-lights clear while the shadows
acquire density. Under-exposed prints can rarely be made to give
passable results with ferrous oxalate. The addition of a trace of
hypo to the developer has been recommended for bringing up their
detail, but the result is far from good.
As soon as development is complete the prints must _not_ be put in
clean water, but must be transferred direct from the developer to
the following acid bath:--
Acetic acid 1 dram
Water 32 ounces
After an immersion of one minute, the operation must be twice
repeated in similar baths that have not been previously used; this
is to remove the iron from the print. A thorough washing must next
be given to remove the acid and the print may then be fixed for at
least fifteen minutes in
Hypo 2 ounces
Water 20 ounces
After fixing (no matter what developer has been used) the prints
must be thoroughly washed in several changes of water for at least
two hours.
The chief reasons against the use of ferrous oxalate are lack of
control over development and the necessary use of an acid bath.
Unless the acid bath is used, the prints will be yellow because of
the iron in them, and if the acid is not entirely removed before
fixing the prints will be yellow owing to the decomposition of the
hypo by the acid in the print which causes deposition of sulphur.
_Metol Developer._--With this, and the other developers I shall
mention, an acid bath is not necessary and so one cause of failure
(and extra work) is obviated. I have somewhat amended the Barnet
formula to meet the needs of workers on a small scale and have also
arranged A and B to balance each other without disturbing the
relative proportions of the ingredients.
A.
Metol 120 grains
Water (cold) 24 ounces
Dissolve _completely_ and then add
Sodium sulphite 2-1/2 ounces
Potassium bromide 15 grains
Shake until completely dissolved but do not apply heat.
B.
Potassium carbonate 350 grains
Water 8 ounces
For use, mix three parts by measure of A and one part of B.
With this developer and a normal exposure, the image should appear
in a few seconds and development should be complete in about two
minutes. As fast as the prints are developed they should be immersed
in
Salt 2 ounces
Water 20 ounces
to stop development. When all are developed, they must be rinsed for
a minute or two in clean water and then fixed. Over-exposure is
remedied by the addition of potassium bromide solution (as in the
case of ferrous oxalate); under-exposed prints should be developed
in a weak solution such as
A 3 parts
B 1 part
Water 4 parts
Development will take longer, but the weaker solution will help to
bring up the detail without the harshness of the shadows that would
be the case if the normal developer was used.
_Hydroquinone and Eikonogen._--The advantage of combining eikonogen
with quinol lies in the fact that one provides what the other lacks,
the eikonogen tending to give detail without density and the quinol
(in inexperienced hands) giving density without detail. The
following formula will be found very satisfactory:--
A.
Quinol 40 grains
Eikonogen 120 "
Sodium sulphite 480 "
Citric acid 20 "
Water to 20 ounces
Dissolve the sodium sulphite and citric acid in 15 ounces of water,
then add the other ingredients and enough water to make a total bulk
of 20 ounces.
B.
Sodium carbonate 60 grains
Sodium hydrate 30 "
Potassium bromide 5 "
Water to 20 ounces
For use, mix one part of A, one part of B and two parts of water.
The same remarks as to over and under-exposure apply as in the case
of metol.
_Toning Bromide Prints._--The "tone" or colour of the deposit
depends largely upon the accuracy of exposure and the developer
employed. Ferrous oxalate gives a rich black deposit, but to my mind
metol and the combined eiko-quinol give tones at least as beautiful
with pretty gray half-tones.
But some people prefer warmer colours, brown and red for instance,
and some get brownish blacks (through over-exposure and the use of
bromide) which they would like to change.
The colour of the deposit may be changed in various ways by treating
the print in baths of different metals. I will give a brief outline
of the methods employed, leaving readers to modify them to suit each
particular case.
_Black and Blue-black Tone._--Brownish black prints can be much
improved after fixing by immersion in a strong bath of gold
chloride; the following is the strength used by me:--
A.
Ammonium sulphocyanide 20 grains
Water 1 ounce
B.
Gold chloride 2 grains
Water 1 ounce
When quite dissolved add B very gradually to A, shaking almost
continuously. The fixed print should be washed for at least fifteen
minutes before toning and should then be placed in a clean tray
while the toning bath is poured over it. The solution must be kept
moving and the print must be removed and washed directly the desired
tone is reached. Prolonged immersion will cause the print to acquire
a deep blue tone.
_Brown and Red Tones with Uranium._--Prints immersed in the uranium
toning bath gradually become warmer in tone, changing from black to
brown and brownish red until they assume a deep red nearly
approaching the well-known Bartollozzi chalk.
Prints to be toned by this process must be _thoroughly_ free from
hypo or stains will be the inevitable result. The toning bath should
be made up as follows, and it must be used at once as it will not
keep after mixing A and B:--
A.
Potassium ferricyanide 20 grains
Water 20 ounces
Glacial acetic acid 1 ounce
When quite dissolved add
B.
Uranium nitrate 20 grains
Water 1 ounce
Immerse the print and keep the solution in motion until the desired
colour is produced, then wash the print for half an hour in several
changes of water acidulated (1 dram in 30 ounces) with acetic acid.
Weak, under-developed prints are much improved by this method of
toning.
At the end of half an hour, if the whites are at all yellow they may
be cleared by immersing the print for a minute or two in the
following bath:--
Ammonium sulphocyanide 20 grains
Water 10 ounces
After immersion, rinse the print for five minutes and dry.
_Intensification._--It sometimes happens (especially when too little
light has been used to properly judge development) that one acquires
a collection of prints that, owing to under or over-development, are
useless; let us see how they may be rendered serviceable.
An under-developed print, though weakly looking and "washed out,"
simply needs intensification to give it the requisite pluck. The
foregoing uranium bath acts as an intensifier while conferring a
ruddy tone on the deposit. A black deposit can be obtained by
intensifying the well-washed print with mercury. The print must
first be immersed in a saturated solution of mercuric chloride until
the image disappears; it must then be again thoroughly washed to
remove all traces of free mercury and may then be redeveloped by
flowing over it an old ferrous-oxalate developer. If ferrous oxalate
is not at hand, an old metol developer may be substituted, but the
former is the more reliable.
When the image is sufficiently intense, the print must once more be
thoroughly washed. All the toning and intensifying operations may be
conducted by daylight.
_Reduction of Density._--Over dense prints can be made fit for many
purposes by means of a "reducer" capable of dissolving part of the
deposit. The best for the purpose and the one least liable to cause
stains is know as the Belitzski's; it is prepared thus:--
Water 60 ounces
Potassium ferric oxalate 3 "
Sodium sulphite 3 "
Dissolve and add to the red solution so obtained.
Oxalic acid 1 ounce
Shake until the solution turns green and then immediately pour off
the solution from any crystals remaining undissolved. To this
solution add
Hyposulphite of soda 15 ounces
and shake until dissolved, when it is ready for use.
The print to be reduced need not be free from hypo, but should be
rinsed for a few minutes after fixing (or soaked until limp, if
previously dried) and may then be placed in a tray and flooded with
the reducer. The tray must be well rocked and the print, when
sufficiently reduced, must be removed without delay and rapidly
washed in running water.
_Some Cheap and Useful Trays._--If large-sized prints are made, the
cost of suitable trays becomes a very serious item. The expense of
these may be reduced to a mere nothing, without loss of
effectiveness, by the substitution of home-made ones. All that is
required to make a tray of any size is a thin wooden confectionery
box (or the bottom part of a larger case) lined with the shiny white
marbled oilcloth known as "American moleskin." This is fitted inside
the box (the corners being turned under) and secured by a row of
tacks around the top edge. No further lining or preparation is
required and the tray will stand all sorts of ill-treatment. As for
durability: I had three such trays made out of old herring-boxes
picked up at Calgary and lined with moleskin that had already seen
service as cover to a wash-handstand and chest of drawers in a
Canadian boardinghouse. For upwards of a year those trays were used
daily and travelled many hundreds of miles by mule and dog train, and
were not worn out when I returned home. My porcelain trays were
smashed by a fall from a refractory mule, but the rough and ready
makeshifts were a priceless boon.
It seems to me that by practising economy of this kind and in
various similar ways (_i.e._, where economy is necessary as,
unfortunately, it sometimes is) the cost of practising our pet
recreation is very materially reduced.
_W. Ethelbert Henry, C.E._
_The Gum-Bichromate Process._
[Illustration]
Pictorial photography is answerable for the revival of this, one of
the almost forgotten methods of printing. Results unacceptable to
bygone requirements have been reintroduced with advantage, where
suggestive individuality and artistic effect have been desired.
The gum process has an unlimited range of possibilities, it would be
impossible to describe them all. The minutest details, or the
broadest diffusion together with the power of working from the
highest to the lowest keys of _chiaroscuro_ are values that can only
be realized when the infatuation consequent on successfully working
the process is experienced.
This method of printing, as with the so-called "carbon process," is
dependent upon the characteristic behaviour of the chromic salts
when in combination with organic substances, such as gelatine, gums
of various kinds, starch, etc.
When any of these mixtures are submitted to the action of actinic
light, they become more or less insoluble.
This property was partially discovered as far back as 1798, by
Vauquelin. Professor Sucrow, Mungo Ponton, Beauregard and others
advanced its application to photography up to about 1840, but it was
not until some ten years later that its great value as a
photographic agent was definitely established.
Hunt, Fox Talbot and Poitevin, each worked indefatigably to bring
the application of the chromic process to a successful issue; but to
Poitevin must be accredited the honour of being the original
inventor of the chromated pigment or carbon process. This brings us
up to about 1855.
None of these investigators appear to have been remarkably
successful, beyond having established definite, but valuable facts
of the changes produced.
This want of success may possibly be accounted for by the general
employment of gelatine and direct printing. It was not until Pouncey
and others, about 1859, employed gum as the colloid medium, that any
great advance was made.
About this time an important commission of inquiry decided that to
Pouncey, Gamier and Salmon, and Beauregard the honour of producing
permanent prints must be equally credited, and accordingly divided
the Duc de Luyue's prize between them, giving to Poitevin the credit
of the priority of invention.
Pouncey appears to have followed up the process with some
considerable success, as some of his existing examples are
excellent; it is much to be regretted that we have not more detailed
particulars of his methods of working; but he evidently was before
his time and met with but little encouragement.
To Alfred Maskell and M. Demachy must be accredited the revival of
this long neglected process, and during the last three years much
advancement has been made towards perfecting it.
Serious workers, both at home and abroad, are industriously
exhausting the possibilities of the process, and crude as some of
the earlier examples of this revival have been, improvements and
simplicity of working are giving us productions of every
description, of such excellent quality that it may soon be expected
to satisfy even the caustic criticism that has so persistently
opposed its re-introduction.
Dexterity in the various stages of practical manipulation is
necessary before skilful efficiency can be secured, and in order to
arrive at this, due consideration must be given to the selection of
the paper the colour most suitable to the subject and the effect
desired.
Almost any kind of paper will be found workable, if it be of fairly
good quality. Those that are thickly coated with soluble sizing
media are unsuitable, for although they may give clear whites they
sometimes produce harsh prints, the half-tones are also liable to be
lost in development unless very deeply printed. Several of the
continental kinds are well adapted to the process and work in an
excellent manner, giving soft and even results; of course, it will
be understood that for definition and fine detail the finer grained
descriptions are the best, but where diffusion is desired those of a
coarser texture may be advantageously used, they give a granulation
that tends materially to secure the peculiarities of gradation
characteristic of this process.
A few of the continental papers that will be found to work with ease
to the beginner, are as follows:--
Michallet paper is rather coarse, but takes the gum coating easily,
it has a series of lines running in both directions, which are
rather objectionable for some subjects; but it is an excellent paper
for first experiments.
Ingrés, is also a paper of similar character, and can be worked with
equal facility. Lallane is another paper of the same class, but much
finer.
Allongé paper is entirely free from the markings peculiar to those
previously mentioned. This paper is best worked on the reverse side,
which can be distinguished by examining the name marked in one
corner.
Among the English papers the ordinary cartridge, Whatman's drawing
papers and many others are adaptable, but it must be borne in mind
that those with a toothed or grained surface are preferable.
There are two methods of working, and results of equal excellence
have been produced by either. Some of the most proficient workers of
the process adopt the easier one of coating the paper, without
previous preparation, with a mixture of gum, bichromate of potass
and pigment. Others adopt the precaution of first saturating the
paper with a strong solution of bichromate, and when dry coating it
with a mixture containing only gum and pigment.
Experience is in favour of the previous saturation of the paper,
this is recommended especially for beginners, as there are several
kinds of paper that will not work efficiently by the first method;
but when skill and practical knowledge of the special behaviour of
the materials employed is acquired, either method can be adopted.
We may presume that the advantage of the previous saturation of the
paper with the chromic salt is, that should there be any inequality
in its structural character, or should it be unequally sized, the
bichromate appears to act as a kind of resist to the penetration of
the pigment, thereby securing an increased range of tone and a
corresponding purity of the whites.
The process may be divided into the following operations:--
Saturation or sensitizing of the paper.
Preparation of the gum mucilage.
Mixing and preparing the pigments.
Coating the paper.
Printing and exposure.
Development.
For working by the previously chromated paper method, the
sensitizing solution is made up of one part of bichromate of
potassium dissolved in ten parts of water. This strength will not
keep at all temperatures. Should the salt crystallize out, it is
necessary to warm a portion of the solution and re-dissolve the
crystals. The solution may be used repeatedly, but it will be
necessary to filter it occasionally.
Before saturation it is convenient to cut the paper into the most
useful sizes--quarter sheets are handy. Having decided which is to
be the working side, mark the back distinctly. Into a dish of
sufficient depth pour in the one in ten bichromate solution to a
depth of about one inch, and immerse your paper sheet by sheet,
until you have in it all you intend to sensitize. As each sheet is
placed in the solution, remove air bells and turn it over and repeat
this precaution. The time necessary for immersion is of no
importance so that the saturation is absolute, about five minutes
being generally sufficient for the thickest of papers. By removing
the bottom sheet to the top and passing through the whole in this
manner, turning over each sheet and removing all air bells, even
saturation is secured. Each sheet is carefully and slowly removed
from the solution and dried in the dark. The paper is now very
sensitive to actinic light, which must during all future operations
be carefully guarded against.
After the paper is dry, it will--if kept so--be in good condition
for a long time.
To prepare the gum mucilage, take two ounces of Soudan or Turkey gum
and dissolve it in five fluid ounces of cold water, strain out the
floating impurities through fine muslin, and allow others, and finer
to subside. This mucilage will keep in good condition in a
well-corked bottle, for a considerable time. M. Demachy employs gum
mucilage of twice this density.
Pigments in powder are more suitable than in any other form, if in
cakes or paste. The medium in which they are prepared, does not work
kindly with the gum, and it is also difficult to accurately measure
quantities. No advantage is gained by using expensive colours, they
can all be purchased at a good colourman's, and at a small cost.
Lamp or any carbon, black, red ochre, yellow ochre, burnt sienna,
and raw sienna, all work well; there is some uncertainty with the
umbers and sepias. It will be found that much time will be saved if
a combination of these dry colours is made up in bulk, as for
instance--one hundred and seventy-five grains of vegetable black and
one hundred of burnt sienna, give a rich soft brown colour. These
must be finely and intimately mixed with each other, which is
conveniently accomplished by grinding with a small pestle and
mortar; after which the mixture may be kept in a wide-mouthed
bottle. Another advantage in thus keeping combinations of dry
colours in bulk, is the absolute certainty of repeating the actual
tint when required.
Various combinations of similar mixtures can be made. Of course it
will be understood that any or all of the above-named colours may be
used singly.
The grinding of the pigment with the mucilage is easily done on a
stone slab with a palette knife. Take half a fluid ounce of the two
in five gum mucilage, to which add the same quantity of water and
thoroughly mix. Weigh out fifteen grains of the mixed pigment and
place in a heap on the slab, add a few drops of the diluted
mucilage, grind and regrind the mixture until it is completely
smooth, then remove it to a cup, and clean the stone with another
portion of the reduced mucilage, finally adding the whole of the
ounce, intimately mix, and it is then ready for coating the paper.
For extra fine work on smooth paper, and in fact for all classes of
work, the fine grinding of the colours adds materially to extend the
range of gradation, and although the trituration may be carried out
fairly well with a palette knife, when the finest possible grades
are desired, recourse must be had to the muller and stone. Mullers
are obtainable of any artist's colourman, they are made in glass,
and a convenient size is about one inch in diameter.
The most convenient brush for applying the mixture of combined gum
and pigment to the paper, is of the description known as bear's
hair, these are usually set in tin; a flat one about two inches wide
is a useful size.
In order to coat the paper evenly, pin it down to a drawing board by
each corner with a double layer of blotting paper an inch or two
larger than the paper to be coated. The blotting paper will absorb
the excess of colour at the margins and enable you to secure an even
coating up to the extreme edge.
Take a fairly full brush of the mixture after thoroughly
incorporating the colour and spread it evenly over the paper,
crossing and recrossing it with the brush. Allow the mixture to lie
upon the paper for a second or two so that the paper may expand; now
release each of the corners and pin the paper down again. Upon the
next operation depends the evenness of the coating.
Take a four inch wide artist's badger's hair softener, hold it
vertically and lightly by two fingers and the thumb about an inch
and a half from the top of the handle, and pass it rapidly over the
whole surface of the paper as quickly and evenly as possible. The
motion producing the best effect is not the usual sweeping action,
but a series of sudden short jerks, difficult to describe but easily
acquired. Continue this softening down until the paper has an even
semi-transparent surface without uneven cloudy spots. Allow it to
dry spontaneously, but before it is stored for future use dry it
carefully by the fire, but avoid overheating.
Uncertainty of result is a defect often brought into argument against
this process; but absolute uniformity is not difficult if strictly
accurate quantities only are employed. With constant strength of
bichromate and gum, uniform weights and combination of pigment,
similarity of repeats are obtained: but these can only be secured when
each sheet of paper is coated identically with its fellow. To get this
evenness the badger hair softener must be washed out and dried after
coating each sheet. This is very quickly accomplished by an energetic
shaking and drying upon a smooth towel. If the paper has been coated
properly, it has an even semi-transparent surface slightly glassy.
Failures often occur from using an excess of pigment and allowing
the gum to become too thick in consequence of evaporation. Excess
of pigment gives dense heavy shadows and increases the difficulty of
printing; excess of gum gives clear high-lights, tending to hardness
and easy solubility endangering the half-tones.
The paper, if it has been correctly coated will work satisfactorily,
if on steeping a small piece of it downwards upon cold water, the
pigmented gum dissolves and drops from the surface leaving the paper
nearly clean. From ten to fifteen minutes should complete this test.
The method of working without previously chromatizing the paper is
as follows:--Take half a fluid ounce of four-in-ten gum mucilage and
add to it an equal quantity of saturated solution of bichromate of
potass; to this, with all care as to grinding and mixing, add the
pigment; coat the paper as before directed. This method will be
considerably slower in printing than that in which the paper had
been previously saturated with the bichromate; neither are the
whites as a rule quite so clear; but it will possess a peculiar
grain and softness not otherwise obtainable, which is much approved
by some workers of the process.
Exposure is so much dependent on circumstances that it is difficult
to give precise directions, being governed by the density of the
negative, the thickness of the coating and the intensity of the
light. Even and not too dense negatives are the more suitable, for
if the intermediate and high-lights are over dense the shadows are
considerably over printed before the lighter parts can be brought
out. Skill in development can do much to overcome these defects, but
they may be considerably modified by the judicious employment of
matt varnish, and by other methods of locally retarding printing.
The greatest assistance in obtaining uniformity in printing is the
employment of a reliable actinometer, Wynne's print meter is
probably the most useful for this purpose, with ordinary
gelatino-chloride paper as a register; from twelve to sixteen
numbers will be mostly sufficient for an ordinary negative, on not
too thickly coated paper. Another method of judging exposure is by
the appearance of the shadows; they may frequently be seen by
transmitted light, and when well out printing may be judged to be
correct, but this is a slovenly method and only approximately
correct at the best.
If the bichromate is used only in the pigmented gum, without
previous saturation of the paper, exposure must be much more
prolonged.
By no other process is it possible to obtain such diversity of
effect as by this; much will, however, depend on the skill which is
exercised in development. Should the printing exposure have been
fairly correct it is a simple procedure. The print is floated face
downward upon cold water contained in a deep dish; see that all
parts are equally acted upon by the water, and that no air bells
exist; if any, they may be easily removed by gently raising the
print and immersing it again once or twice. After it has been
soaking some five or ten minutes it may be examined; if all is going
well, and the exposure has been approximately correct, the pigmented
gum on the unexposed margins will have left the paper, and possibly
some of the high-lights and half-tones may be making an appearance,
if so, the treatment must be of a gentle character, and the print
may be safely left for some time longer in the same position face
downward; never allow it to lie either in or out of the water face
upwards for any long time, or unremovable stains will be developed.
Many prints will develop almost entirely without assistance, or
with only an occasional laving of water if allowed to lie in this
position for a long time. On the other hand some may, even when only
slightly over-printed, give no indication of development. When this
is the case remove the print from the water and place it face
upwards upon a thin, smooth board, fix it in position with one
drawing pin on the extreme margin, then gently lave cold water over
it; should some of the darker parts still resist this action, longer
soaking will be found advantageous. If there are still parts on
which the colour will not move, recourse must be had to the brush,
and for this purpose nothing is better than a large camel's hair
mop. Keeping the brush always full of water, touch where necessary
very softly; do not sweep it up or down, but just dab here and there
as may be required, constantly flowing over the surface a copious
supply of water.
If there are still parts in the shadows, or even in the high-lights
that will not move, a jet of water from an enema syringe or from the
household service pipe is very useful.
As a last resource a prolonged steeping in water of varying degrees
of temperature, even up to the boiling point, may be resorted to,
but the application of increased temperature requires judicious
management.
When the print is sufficiently developed, if the creamy yellowness
of the chromate stain is not desired, the print must be cleared or
bleached, either in a solution of alum, sulphite of soda, or
hyposulphite of soda, strength being immaterial with a careful
after-washing. If the print is only just sufficient or only slightly
over-printed, care must be taken that the clearing bath is not acid,
neither must the washing be too prolonged, but if the print is
first dried and submitted to light, this precaution is unnecessary.
Always allow the prints to dry spontaneously. It will not do to use
any kind of pressure or blotting paper, for the surface of the
colour is very tender and delicate.
_Jas. Packham, F.R.P.S._
_An Introduction to Carbon Printing for Beginners._
[Illustration]
In the article that follows next will be found a complete exposition
of the carbon process, with its various adaptations from the
preparation of the paper and material forwards.
Whilst at the present time carbon printing is more largely used by
professional photographers, yet its simplicity, the absence of
chemical formulæ and complications combined with the beauty of the
results, makes it eminently suitable for amateur workers, and hence
it has been thought desirable that as an introduction to the
subsequent article, a brief and simple outline of the process should
be given for the benefit of those who have not hitherto made its
acquaintance.
In the first place then let it be understood that in carbon printing
instead of depending on light to make a visible alteration of the
sensitive salts as in silver printing, we expose the prepared paper
or "tissue," as it is called, under a negative and secure a positive
in insoluble gelatine, the gelatine having combined with it a
pigment, and hence we get an image in pigment, not in platinum, or
silver, or gold, but in a simple pigment which may be of any colour.
If bichromate of potash is mixed with an organic substance such as
gelatine, that gelatine becomes insoluble after exposure to light,
and if that gelatine carries with it a pigment, then on becoming
insoluble it holds the pigment with it. If now, paper or other
material be coated with bichromate, gelatine, and pigment, and
exposed to light under a negative in the usual way, the thin
portions of the negative will admit of the light acting on this
coating and making it insoluble, whilst the parts which are
protected from light, as for instance the sky or white objects, will
remain unchanged and soluble, and on being washed in water will
dissolve away, leaving white paper, whilst the light-affected
portions which have become insoluble remain in proportion as the
light has penetrated the various densities of the negative. This
then is how we obtain our print.
For fuller explanation of the paper or "tissue" and its manufacture
the reader is referred to the next article.
The beginner will certainly first obtain his tissue ready made, and
he can purchase it ready sensitized or otherwise. The former will be
best at the outset, but it must be borne in mind that it should not
be kept longer than can be helped before use, and never more than
ten to fourteen days at the utmost. Various shades of blacks,
browns, and reds are the usual colours, also grey, green, and blue.
The tissue is rather more sensitive to light than silver paper, and
should therefore be opened and handled in subdued light. It must be
kept as dry as possible. A rather vigorous negative is best for
carbon printing, one not too strong in contrasts. Before placing the
negative in the frame, we must give it what is termed a "safe edge."
This is done by making a narrow border, say of about a quarter of an
inch or less, round the negative, either on the glass or film side,
with opaque black varnish, or it may be done by gumming on narrow
strips of paper, such as lantern-slide binders. If binders and not
black varnish are used, they must be applied to the glass side.
The Carbon printing paper which will hereinafter be called the
"tissue" will be found to present an unpromising appearance, and as
the coating is the full colour of the pigment in which the print is
eventually to appear, it follows that the progress of printing will
not be visible, and a mechanical means of gauging the exposure must
be resorted to. An actinometer, similar to that described in the
article on Platinotype, will do, and another and simpler form is
described in the next article.
Printing will occupy about one-third of the time occupied by
gelatino-chloride of silver paper.
Development is conducted in daylight, but not too close to a window.
The absence of chemical solutions has been suggested as an
advantage, in this process the developer being merely hot water.
It is not necessary to have this laid on, a can of hot water close
at hand and a kettle on the fire or gas stove not far off are all
that are required.
We shall require four or five dishes, one at least of which should
be a good deal larger than the size of the prints we are to develop
and several inches deep--a good-sized pie-dish or a basin will do.
Development merely consists of washing away the unaffected and
therefore soluble coating, but it must be remembered that the less
affected portions representing the half-tones have received their
modicum of light on the surface, and therefore the soluble part of
the film is underneath the part that has like a surface skin become
insoluble. This necessitates the printed film or tissue being
transferred to another paper or "support," so that we may develop or
wash away from the back.
In procuring your carbon tissue order at the same time a packet of
Single Transfer Paper, which is paper with a thin coating of hard
gelatine. Now to proceed. Place a piece of single transfer paper
into a dish of cold water, and in three or four minutes the coated
side will feel slimy, then place in the same dish a piece of the
printed tissue face upwards. This will probably curl up at first and
afterwards flatten out again. When this has happened or in a few
minutes after immersion bring the piece of single transfer paper and
the print together, film to film, so that they may be in contact,
and square one with the other. Now holding them by one edge,
withdraw them together by sliding them out of the dish on to a sheet
of thick glass, a large cutting glass serves well, or stout sheet of
zinc.
This should be supported in readiness at the rim of the dish.
Having the transfer paper and print now on the glass or zinc, hold
them firmly and with a rubber squeegee press them closely into
contact, squeezing as much water out as possible.
A better way perhaps is, if the dish is large enough, to place the
glass or zinc under the two papers whilst in the water and so raise
them out.
The squeegeeing must be done thoroughly, firmly, and all
over--several strokes being given in each direction.
Next lift the papers, now in firm contact and sticking together, and
place them between blotting paper on which is a heavy weight. The
next print may now be proceeded with and so on.
The print should be between blotting paper and under pressure for
about twenty minutes, after which it is removed to a dish of hot
water--almost as hot as the hands can comfortably bear, say 100° to
120° F.
After lying in this for a few moments the dark pigment will be seen
to be oozing out from between the two papers. When this has begun to
come pretty freely take one corner of the print and pull it away
from the transfer paper. It should come quite easily, and on being
peeled off entirely it is thrown away. We have now the transfer
paper bearing the printed film reversed, that is, the side which was
previously at the bottom and next the original paper support, is now
uppermost and can therefore be got at.
If we splash it or lave it with the hand, using the hot water, we
shall soon see what happens. The smudgy mass of pigment begins to
wash away and the picture gradually appears.
This constitutes development and we continue working it with hot
water until the whole is clear and bright, being careful not to
touch the film with fingers or anything but water, for being in a
very delicate and soft condition it would be certain to sustain
injury.
The hotter the water the greater its washing-off action, and hence
in cases of over-exposure very hot water may go far to recover the
print. When the desired result is secured, transfer the print to a
dish of cold water, this instantly tends to slightly harden the film
by cooling it, and after two or three minutes it is passed into a
dish of alum and water, which further hardens it and also "clears"
the print of any bichromate salts which may still remain. In the
alum bath the print should remain until any sign of yellow stain has
disappeared, when after a final rinse of a few minutes in cold water
to remove the alum, the print may be hung up to dry.
It will be seen that there is no prolonged washing as with those
processes in which hypo is employed, and the print is absolutely
permanent.
It must be remembered, however, that in the finished picture we are
looking at the back of the printed film as it received the light
impressions from the negative, and hence the image is reversed, that
is, the left is on the right and the right on the left. For
landscape and views this reversed position will probably be of no
importance, but if it is desired to have things right way round--in
portraits it will be essential--we must either work from reversed
negatives, or we must again transfer the film which will then
constitute a _double_ transfer. We shall now understand why
previously we called the paper to which the film was transferred
_single_ transfer.
Inasmuch as it will be seen that the print is not on paper, but
consists of a transferable film of pigmented gelatine, it will be
understood that the paper employed is merely a support to that film,
hence it is customary to speak of the paper as the support, whilst
moreover it maybe, and as often as not is ivory, glass, textile
fabrics, wood, or other substances.
If now we wish to again transfer the film so as to correct the
lateral reversal, we substitute for the single transfer paper a
"_temporary_ support."
The temporary support which is to receive the film merely whilst it
is being developed, and with the intention of its being subsequently
transferred again to a _final_ support, may be paper or many other
things.
Moreover, remembering that the film is mainly gelatine, it should be
clear that whatever the nature of the surface of the temporary
support, the soft glutinous film will take that surface just as we
may make the impression of a seal in sealing-wax.
The normal carbon print is shiny, due to the gelatine, and so, if as
a temporary support we were to use ground glass or matt "opal," the
carbon print film would receive the fine granulated surface and give
a matted print as a result. This merely by the way as suggesting an
additional advantage offered by the double transfer process as a
set-off against the slight extra trouble.
If double transfer is determined upon, and it is not intended to
experiment with ground glass, etc., then when purchasing the carbon
tissue, some _temporary_ support (sheets of paper coated with
gelatine and shellac) should be procured, also some pieces of
_final_ support.
Whatever the temporary support, it must receive an application of
waxing solution. This also may be bought, or can be made of:--
Yellow resin 36 grains.
Yellow wax 12 "
Ether 2 ounces.
Melt the wax, add the resin, stir together and then add the ether.
Pour a little of this mixture on to the temporary support and spread
with a tuft of cotton wool, and rub over to make it even.
The final support for double transfer may be purchased, and is made
ready for use by soaking for ten minutes in alum.
The temporary support, after being waxed and the waxing solution
having become dry, is to take the place of the single transfer paper
in every respect, and the film developed as already described. When
it has reached the final washing, after the alum clearing bath, it
is brought into contact with the final support (which has been for
ten minutes in alum bath as just described) and is removed to the
glass or zinc plate and squeegeed.
It is now hung up to dry, and when quite dry the blade of a knife
should be inserted at one corner and the temporary support gently
pulled off.
Such is the carbon process, neither difficult nor lengthy, and with
this brief outline to form an introduction, the reader who is a tyro
will the better appreciate the fuller description which follows.
* * * * *
Whilst the article that follows is more comprehensive than the
beginner may require at first, he is nevertheless advised to read it
carefully through, and some points which may not seem clear at first
will explain themselves after a very little experience.
_The Carbon Process._
[Illustration]
Before proceeding to practical details of working, it may be as well
to realize what a piece of carbon tissue is, and what takes place in
the process of exposing such tissue to light. Mr. J. W. Swan, who is
to be regarded as the inventor of carbon process as we now know it,
was justified in giving the name "tissue" to the film of pigmented
bichromatized gelatine, as at first it was a tissue unsupported by
paper backing and containing pigment practically, if not entirely,
carbon. The terms "carbon" and "tissue" have been generally accepted
as describing a pigmented paper containing permanent colour,
therefore little if any misunderstanding is caused by such general
description. The carbon process, like other kindred methods, is
based upon the well-known hardening action of light upon a
bichromate salt in combination with organic matter. When paper is
coated with a mixture of gelatine pigment and a bichromate salt,
dried under favourable conditions and exposed to light under a
negative it naturally follows that a positive image is produced. The
negative acting as a screen, prevents any undue hardening of such
portions of the picture as are intended to form the high-lights,
only slightly interfering with what are to be the middle tints, and
practically permitting full play in the shadows. The latent image is
imprinted on and into the film of tissue compound with the most
delicate portions on the surface, and means must therefore be
adopted to protect the surface during the washing away of all parts
of the film not intended or desired to form any part of the finished
picture.[7] In Swan's process this object was secured by cementing
the surface of the printed tissue to its temporary support with
rubber solution, but after J. R. Johnson discovered that the printed
tissue would adhere without any cement to any surface impervious to
air and water simply by atmospheric pressure, the same end was
gained by soaking the undeveloped print in water until about _half
saturated_, then bringing it into contact _under water_ with either
its temporary or permanent support, slightly squeegeeing or sponging
to remove as much water as possible without injury to the print; as
to _air_, _there ought not to be any present_ if care is taken to
exclude it before lifting from the water bath. The half-soaked
tissue after mounting absorbs every particle of water from between
the surfaces, and thus secures optical contact.
[7] It is generally asserted by non-practical carbon printers
that all portions of the film behind that which finally forms
the print, are unacted upon by light. That is to say,
unchanged and quite as soluble as if not printed at all. The
upholders of such a theory should try the following
experiment:--Take a piece of tissue, cut it through the
centre, expose one piece, then mount both under precisely
similar conditions and wash in the same warm water bath.
Paying special attention to the backing papers, they will
find the one unacted upon by light will have parted with its
load of coloured material in much less time than the piece
that formed the backing of the print.
The squeegee, handy tool as it is, ought to be used with great care,
in no case with any degree of force, or serious injury will result,
particularly to the finer kinds of work, such as double transfer
prints of all kinds, either on paper, ivory or opal. The rubber edge
of the squeegee should be free from notches, often caused by contact
with the sharp edges of glass plates. The notches can be removed by
rubbing on a sheet of glass paper placed on a plane surface.
TISSUE MAKING.
The tissue compound consists of a mixture of the following
ingredients:--Gelatine, sugar, pigment and water. The proportions
are of infinite variety according to season, the nature of the
pigment used, and the purpose for which the tissue is intended. For
convenience it is the rule for tissue makers to prepare what is
termed stock jelly by dissolving, by the aid of a water bath,
gelatine and sugar in water, in varying proportions--roughly
speaking:--
Gelatine 2 parts.
Water 4 to 7 "
Sugar[8] 3/4 to 1-1/4 "
[8] For some purposes (instead of sugar), glycerine, sugar of
milk, or treacle may be substituted.
The pigments are made up into what are termed jelly colours, which
are ground either by hand on a slab of glass, marble or granite,
using a suitable muller for the purpose, or when large quantities
are required a paint mill driven by steam or other power is
employed. In hand grinding the colour is kept moist by syrup on
greatly reduced stock jelly. After grinding by hand the pigment is
lifted from the slab with a palette knife and stirred into melted
stock jelly. When the mill is used, the pigment is mixed with the
jelly before grinding. The proportion of pigment to jelly varies
enormously according to the nature of the pigment, and may be
anything between 2-1/2 per cent. and 25 per cent. Having prepared
stock jelly and jelly colours, and allowed both to set, they are
weighed out in proper proportions, the jelly being dissolved in a
tin vessel placed in a water bath. The colour, generally speaking,
is dissolved in a small proportion of the stock jelly placed in the
mill and again ground into the bulk of the jelly. In some cases the
pigment is dissolved in warm water and filtered through cotton wool,
fine felt or flannel. After adding powdered recrystallized
bichromate, the jelly compound is ready for coating or spreading on
the paper. The coating may be done by hand or machine. Several forms
of machine are in use, including the first form invented by Mr.
Swan. When only a small quantity is required, it is the general
practice to coat by hand.
In hand coating, the tissue compound may be strained through fine
muslin into a flat tin dish placed on a water bath; the surface
cleared of air bubbles by dragging over it a strip of stiff paper.
The sheet of paper to be coated is held in an upright position at
the further end of the dish with its bottom edge just touching the
surface of the solution, gently lowered until the whole surface of
the sheet is in contact with the solution. If the lowering is
properly done there will not be any default in contact, but if
allowed to rest on the solution a few moments, the presence of air
bubbles, if any, will be detected by the presence of little lumps on
the back of the paper, these may be removed by raising a corner
and touching the spots with a finger tip. The sheet is then raised
with a rather slow and steady motion, allowed to drip, then clipped
to a line by its top corners and left to dry in a warm dry room from
which white light has been excluded. When this method of coating is
adopted it is best to have the sheets of paper an inch longer than
the dish; the blank edge prevents contamination of the fingers and
distortion of the sheet caused by contraction in drying. Another
method of hand-coating is to roll the sheet into a tube shape,
placing the roll on the surface of the jelly compound one and a half
inches from the top of the free end, raising with rather slow and
steady motion as before. When the second method is chosen an oblong
and somewhat deep dish will be found better than the flat shape; the
flat dish may be used if tilted to give greater depth of solution in
a corner.
[Illustration: AT THE FOUNTAIN. J. W. WADE.]
In the manufacture of tissues the greatest care must be taken to
avoid over or long-continued heating of the gelatine solution.
Either a too high temperature or a lower temperature, long
continued, destroys the solution by rendering a considerable portion
of it soluble in cold water and to a great degree reducing its
gelatinous character.
The samples of gelatine used in tissue making are of two kinds,
although both of good quality they differ in solubility, in hot
weather a larger proportion of the "hard" sample is used, in cold
weather _vice versa_.
INSENSITIVE TISSUES.
All insensitive tissues are made with a single sample of hard
gelatine. They are stocked by dealers and must of necessity be fit
for use at any season of the year, to say nothing of those exported
to hot climates.
TRANSFER PAPERS.
Papers of many kinds are necessary for single transfer prints, the
tint of the paper must blend and harmonize with the tone of the
tissue or by contrasting help to produce a pleasing effect. For
prints of warm tones such as red chalk, terra cotta and the various
tints of sepia, a yellowish or cream-toned paper forms the most
harmonious basis; the various tints of black, blue, and purple look
best on a slightly bluish-tinted paper. For instance, a copy of an
old engraving in tissue, of the brown tone of the original would be
utterly spoilt by a blue-tinted basis. The above remarks apply only
in a limited degree to double transfer papers which in general use
are confined almost exclusively to portraiture. Such papers are
sometimes modified by tinting mauve, rose, opal, etc., etc. Such
tints are only in small demand and are in all cases confined to
papers coated with enamel preparations. The best and most durable
form of double transfer paper is that prepared on fine chemically
pure paper with colourless gelatine and made insoluble by the
smallest possible quantity of chrome alum, entirely without white or
tinted pigment of any kind. The best variety of double transfer
paper only differs from the finest form of single transfer paper in
having on its surface a rather thicker and softer coating of
colourless gelatine.
All transfer papers, either for single or double transfer, may be
coated in the same way as tissue, with the exception of those having
a very rough surface. All drawing papers and in fact all papers of
very rough surface are prepared by brushing over their surfaces
several coatings of a very thin solution of gelatine containing a
larger proportion of chrome alum or formalin than is used in making
ordinary single transfers. A flat camel-hair brush is best for this
form of coating, care must be taken to avoid air bubbles.
FLEXIBLE TEMPORARY SUPPORT.
Is paper coated with a gelatine solution in the first instance, and
after drying, again coated with an aqueous solution of shellac.
SENSITIZING THE TISSUE.
Pour the bichromate solution into a deep flat dish (porcelain,
ebonite, zinc, wood or tin) to the depth of half an inch to an inch;
place a sheet of tissue in it face upwards, remove air-bubbles with
a camel-hair brush or soft sponge, using as little pressure as may
be; turn the sheet and remove bubbles formed on the paper, turn the
sheet again face upwards, and passing brush or sponge gently over
the surface, keep it evenly wet until it is fairly limp; remove from
the solution, place face downwards on a perfectly clean glass or
zinc plate, squeegee to remove excess of solution, blot or wipe with
a soft cloth, remove any solution from the fingers, lift from the
plate, handle by edges only, clip to a line, small sizes by one
corner only, larger sheets by two corners, leaving a little
slackness between the two clips to allow for contraction in drying,
otherwise the sheet will be distorted and difficult to press into
contact with the negative.
The sensitizing _may_ be done in ordinary daylight. The drying
_must_ take place in a room from which actinic light is excluded,
and in a current of warm dry air, free from impurities, such as the
products of combustion from burning gas, or an escape of sewer gas,
etc., and at a temperature not higher than 120° F. The drying should
be done as quickly as possible, otherwise the tissue's keeping
property will be greatly reduced, and in all probability a thin film
formed on the surface, of insoluble gelatine, known to printers as
"decomposed tint," degrading the high-lights, and, except in the
case of very "hard" negatives, spoiling the work.
It will be evident to anyone that the fancy forms of sensitizing
have been carefully avoided--floating on the back, floating on the
face, etc., etc. All the results desired can be obtained by
immersion. If a hard negative has to be dealt with, a stronger
solution, or longer soaking in the bichromate solution, is all that
is needed; for weak negatives _vice versa_.
_Note._--In the dry frosty air of winter, sensitized tissue will dry
without heat, and continue soluble for a considerable length of
time, often as long as a month, or even longer.
In hot weather it is recommended that the solution of recrystallized
bichromate be made immediately before using, as in dissolving the
crystals a considerable reduction of temperature is produced. Should
the temperature then be over 60° F., ice must be used, not in the
solution, but roughly broken up and mixed with salt in an outer
vessel. If ice is placed in the bichromate bath allowance must be
made by keeping out part of the water. The ice should be encased in
several thicknesses of fine muslin to prevent the solid impurities
it generally contains getting into the solution. When recrystallized
bichromate is not procurable, a few drops of liquid ammonia added to
solution of crude bichromate is recommended. As bichromate is cheap,
a fresh solution should be made for each large batch of tissue.
PRINTING THE NEGATIVE.
Any negative that will yield a thoroughly good albumen print is
suitable for carbon work. The thinner negatives now made for P.O.P.
and similar processes are less satisfactory for direct prints in
carbon, for enlargements and reproductions such negatives can be
made to yield most satisfactory results by modifying the
transparency and the enlarged or reproduced negative. The latitude
in this direction is great. No matter how flat the original negative
may be, _if all the grades are present_ it can be manipulated in
such a way that the most brilliant result will be produced.
PREPARATION OF THE NEGATIVE FOR PRINTING.
The negative is prepared for printing as in all other processes by
removing all defects such as pinholes, streaks, etc. For the carbon
process the negative requires to be further provided with what is
termed a "_safe edge_;" this is a line of black varnish, from
one-eighth to half an inch in width according to the sizes of the
negatives, painted on its margin, either on the film or glass side.
In the case of original negatives masks of opaque paper are used
instead of the painted edge, the masks having openings cut in them
slightly less than the size of the negative. The purpose of the safe
edge is to secure a margin on which light has not acted, as such a
margin gives greater freedom to the operator in the process of
development by preventing the more deeply printed portions of the
picture leaving the support when the backing paper is removed.
DOUBLE TRANSFER PRINTING.
It may be explained in a few words why an ordinary (non-reversed)
negative must be printed by double transfer. In all other solar
processes when the print is removed from or taken off the face of
the negative, it is turned over to view, it therefore follows that
the details on the left side of the negative are found on the right
side of the positive print; with the carbon print no such turning
occurs, it is mounted upon its support in the same position as it
lay on the negative, developed in that position from the back and
leaving the position of objects the same as in the negative. In
some cases this reversal of the position of details is unimportant.
We will first consider the double transfer. In all double transfer
processes a temporary support must be provided. Such supports are of
two kinds, flexible and rigid. When a matt-surface print on paper is
required, finely grained opal glass is used. For the enamelled
surface patent plate, for intermediate or only slightly glazed
surface, a flexible support is used. Flexible support yields a
surface similar to an albumen print without special preparation.
When the higher glaze of the double-albumenized print is desired,
the printed tissue is coated with thin collodion before mounting on
the flexible support. Rigid supports, zinc or ground-glass plates,
have been used, but owing to the difficulty of seeing the details
during development their use is practically discontinued. Flexible
temporary support is always used in transferring to canvas, wood
panel, opal, ivory, etc., etc. In the case of canvas, the double
transfer process has two great advantages. First, staining is
avoided, the bichromate has been thoroughly got rid of in the
process of development. Secondly, the canvas is prepared to receive
the print by a substratum that allows the carbon image to expand and
contract with the expansion or contraction of the canvas and not in
opposition to it. There are also two advantages in adopting the
double transfer process for the production of pictures on ivory. The
first, is freedom from bichromate stains. Secondly, the ivory is not
distorted by washing in hot water, such distortion generally takes
place when the single transfer process is adopted. Wood panels are
prepared in a similar way to canvas. Stains are avoided, and as
there is not the expansion and contraction of canvas to provide
against, the substratum is modified in composition and greatly
reduced. The stains above alluded to are caused by the chemical
combination of bichromate with the lead of the paint, forming
chromate of lead or chrome yellow. In the case of opal, opaque
celluloid, and similar substances, no staining takes place, the
double transfer is only required to restore the image to its proper
position.
SINGLE TRANSFER.
The single transfer process is practically the only method in use
when large sizes or large numbers of prints are required. For large
sizes the negatives are reversed in the process of enlargement. For
small sizes one or more reproduced reversed negatives are made,
either in the camera from a carbon transparency, or by contact
printing from a carbon transparency on a dry plate. With reasonable
care, little if any loss of quality occurs in reproduction. As the
single transfer process is the most simple form of carbon printing,
it is generally recommended to beginners. Probably the most simple
form of all is single transfer on opal. The opal plate does not
require any preparation beyond cleaning. Neither soap nor grease of
any kind must be permitted to contaminate the surface, otherwise the
print will fail to adhere. Opal plates are cleaned by scrubbing with
fine graining sand and water, and a muller or a small plate, either
of ordinary or opal glass, placed upon the wetted sand and moved
over the surface with a circular motion until soiled or discoloured
markings are ground off.
THE ACTINOMETER.
An actinometer must be used to gauge the amount of exposure, as only
a faint image, and in some tissues none at all, is visible during or
after exposure. The simplest form of instrument is the best. That in
general use is known as Johnson's Actinometer, a square tin box
containing a long strip of sensitive albumen paper, and provided
with a glass lid painted to the colour of printed albumen paper, an
opening in the paint in the form of a slit three-sixteenths of an
inch in width, from which the paint has been removed. The strip of
sensitive paper is made to pass between the top of an inner lid and
the painted side of the glass lid underneath the clear slit with the
end of the strip protruding at one side of the box. On exposure to
light the sensitive silver paper gradually discolours until it
closely resembles the colour of the paint, that is called one tint;
the tint is changed by pulling the slip forward just the width of
the slit, and so on until the requisite number of tints have been
printed for the strongest or densest negative in the batch exposed,
those negatives requiring less exposure are turned down or removed
when the requisite number of tints are registered in each case.
EXPOSURE.
For double transfer from opal the materials required are opal
plates, sensitive tissue, French chalk, collodion, double transfer
paper, pressure frame, flat camel-hair brush, chamois leather.
Before placing the negative in pressure frame, carefully clean from
both sides all finger marks, etc., with the leather, place negative
in frame on a paper mask, or provided with a safe edge. After
exposure to light, remove from frame and develop on plate prepared
as follows:--Rub the whole surface with French chalk on a pad of
muslin, afterwards removing loose particles by gentle brushing. Coat
with collodion made as follows:--Enamel collodion, 1 part; ether, 1
part; alcohol, 1 part. Filter and coat by pouring a pool on centre
of the plate, and, by tilting it, force the collodion to flow into
the top right corner, then to the left, then to bottom left, and
finally drain off at bottom right corner, rocking the plate the
while. The collodion must be allowed to set until it will bear the
gentle pressure of a finger in its thickest part, but must not be
permitted to dry in any part before plunging into clean cold water
to remove the solvents by washing. The time required in washing is
variable according to time of year. When the collodion ceases to
repel water it is ready to receive the printed tissue. Soak the
tissue for the requisite time, but not so long as to become quite
saturated, bring it into contact with collodionized side of plate,
remove to squeegeeing board, place over it a piece of wet rubber
cloth, or a piece of wet thick single transfer paper, coated side
up, to prevent injury to exposed margin of collodion and to
facilitate the smooth passage of squeegee over the surface in
removing excess of water. If, on removing the covering from the
plate, the back of tissue is found to be unevenly wet, blot or place
plate in a rack to drain; in a few minutes develop in warm water,
temperature 90° to 100° F. Be careful to remove the backing paper
_under water_, _and as soon as possible after immersion_ in the warm
bath. Finish development by laving or pouring warm water over the
print from jug or other vessel, until all details are brought out.
When washing is finished the print should look rather light, as in
drying a decided increase in strength is obtained; rinse _slightly_
in alum solution to stop bleeding only, place in clean cold water to
wash out any remains of bichromate, thoroughly rinse by dashing
water upon the print to remove any particles of solid matter that
may have stuck to its surface; place in a rack to dry, and transfer
as soon after drying as possible. The transfer paper is cut a trifle
larger than the net size of the print, but less than the opal
support; it is soaked in warm water until the surface is slimy to
the touch, but not soft enough to break under pressure between
finger and thumb. The softened transfer paper is placed in clean
cold water into which the dry print is plunged, water dashed upon
its surface to remove air; the two surfaces are brought into contact
under water, and squeegeed into contact as in first mounting before
development. When thoroughly dry, the print may be removed from the
opal plate by inserting the point of a knife at the edge.
Double transfer prints with enamelled surface are produced precisely
as above, only substituting patent plate for ground opal, and by
adding a second thickness of paper to the back of the finished print
before removal from its temporary support.
DOUBLE TRANSFER FROM FLEXIBLE SUPPORT.
The flexible temporary support is prepared by waxing. The waxing
solutions are:--
No. 1.
Benzol 1 oz.
Pure beeswax (natural not bleached) 3 grs.
No. 2.
Turpentine 1 oz.
Yellow resin 10 grs.
After dissolving, mix the two solutions, pour a little of the
mixture on fine flannel, rub it over so as to evenly moisten the
surface of the flexible support, wipe off with a second flannel
using only slight pressure but rubbing briskly and with circular
_motion_. When finished, the waxed surface should be perfectly even
and quite free from streaks or other markings. The waxing should be
done some considerable time before the support is required for use,
and exposed to the free action of air to remove all trace of the
solvents.
PAPER PRINTS WITH ORDINARY OR SLIGHTLY GLAZED SURFACE.
After removal from the pressure frame, the tissue is plunged into
cold water with a piece of support slightly larger. After soaking
the necessary time, the prepared surfaces are brought into contact
under water, removed from the bath and placed upon any even plane
surface, such as zinc, glass, etc., squeegeed into contact, blotted
or otherwise treated to remove uneven dampness, and developed in
warm water as in double transfer from rigid support, then slightly
rinsed in alum solution and washed in clean cold water until all
traces of bichromate are removed. After the transferring is done as
before described, only the print on flexible support must be soaked
in water until quite flat before bringing into contact with its
final support.
PAPER PRINTS WITH HIGHLY GLAZED SURFACE.
The printed tissue after removal from the pressure frame is coated
with collodion, for this coating allowance must be made in printing.
A considerable reduction in temperature takes place and any moisture
present in the air is condensed on the tissue, bringing into action
the well-known effect of continued moisture, _i.e._, considerably
increasing the depth of the print. Great care must be taken to coat
evenly and to prevent the collodion running in streaks on the back
of the print. When such streaks or unevenness of any kind are
present, a corresponding dark line or lines will be found on the
face of the finished print. Transfer same as for prints with
ordinary surface. All prints from flexible support on paper with a
highly glazed surface as well as those intended for transfer to
ivory or opal are coated with thin collodion:--
Enamel collodion 2 parts
Ether 4 "
Alcohol 4 "
DOUBLE TRANSFER TO OPAL AND IVORY.
After development the print is allowed to dry, and as soon after
drying as possible it is transferred to its final support, whether
opal or ivory, by a solution of gelatine composed of the following
ingredients:--
Gelatine (fairly hard) 1-1/2 ozs.
Water 20 "
Chrome alum solution (30 grs.) 2 "
Soak the gelatine in the water until quite limp, dissolve by heat,
then add the 30 grain chrome alum solution; roughly filter through
two or more thicknesses of fine muslin into a flat dish on a water
bath. After cutting the print to a size a trifle less than opal or
ivory, place both print and final support in gelatine solution,
allow print to stretch until quite flat, then bring them into
contact under solution, squeegee and place on edge to dry. When
quite dry, remove temporary support by inserting the point of a
knife between the surfaces at the edge, wash with benzol or ether to
remove all traces of the waxing solution. The print is now ready for
the artist.
DOUBLE TRANSFER PRINTS ON CANVAS.
For double transfer prints on canvas, as a basis for oil painting,
there is not at the present moment a large demand. A strong
prejudice exists, and deservedly so, against such prints, for the
following reasons. Some thirty years ago, in the principal
establishment in which carbon work was done, a process of printing
on canvas was in vogue. It was roughly this:--A stretched artist's
canvas without other preparation was coated with dammar varnish;
after drying, the canvas was used in pretty much the same way as
single transfer paper is now--that is to say, a piece of printed
tissue was squeegeed into contact with its surface, developed by
floating on hot water, and practically in that crude condition
placed in the hands of artists for oil-colour painting or finishing
as it is sometimes prudently called. The natural result
followed--_viz._, in a dry warm room the canvas stretched, the film
of unmodified gelatine contracted; hence cracks, peeling, etc.,
until the work, valuable or otherwise, was utterly ruined. The
method of preparing the canvas for the reception of the carbon image
introduced by the writer is based upon opposite principles, as
mentioned in the preceding general remarks, and may be described as
follows:--A yielding and elastic substratum of gelatine forms a
crust, so to speak, that expands and contracts according to the
corresponding behaviour of the canvas support.
Ordinary painted canvas, such as is used by artists, or strong linen
may be used with special treatment.
PREPARATION OF PAINTED CANVAS.
The canvas is first stretched tightly on a drawing board, same size
as picture required, the greater part of paint removed by scrubbing
with soda solution (either nail brush, sponge or a piece of flannel
will answer the purpose) until the surface of the fabric is exposed
and little of the paint remains beyond the priming. After drying,
the canvas is coated with the following solution, applied with a
flat camel-hair brush. Several coats (three in cold, four in warm
weather) are given, drying between each and rubbing with fine sand
paper if at all uneven.
Coating Solution.
Cooking gelatine (Cox's soup answers perfectly) 4 oz.
Sugar 2 "
Glycerine 2 "
Water 30 "
30 grain chrome alum solution 1 "
The print is exposed in the ordinary manner, developed on temporary
support, allowed to dry and transferred to the canvas as
follows:--The canvas is placed face upwards, on a level surface by
preference, on a broad board over a large tank. The dry print is
placed face upwards in a flat dish, the warm coating solution poured
over it, air bells removed with the brush, the surface of the canvas
brushed over with the solution. The bulk of the solution is then
poured on the canvas and before it has had time to run off the print
is lowered carefully and quickly upon it and squeegeed to remove
excess of solution. After thorough drying, the temporary support is
removed, the surface of the print cleaned with benzol or ether or a
mixture of both to remove every trace of the waxing compound, and
mounted on a stretcher in the usual manner. A print on canvas
prepared as above, is perfectly reliable, it will neither crack nor
peel, and can be used with perfect confidence as a basis for the
most costly form of artistic finishing, as the carbon image rests
upon an elastic substratum in actual contact with the fibrous
substance of the canvas.
TO PREPARE ORDINARY STRONG LINEN OR CALICO.
Proceed precisely as for painted canvas (of course without
scrubbing), using the same coating solution with half-a-pound white
pigment added, sulphate of baryta answers perfectly. Sand or glass
paper must be used pretty freely as the surface of the unpainted
fabric washes up roughly when the gelatine coatings are applied.
WOOD PANELS.
Wood panels are prepared by removing the surface of the paint only
with soda solution. After drying, a tooth is given by rubbing with
fine sand paper and coating with solution as under:--
Gelatine (Cox's soup) 3 oz.
Sugar 1 "
Glycerine 1/2 "
Water 30 "
30 grain chrome alum solution 3/4 "
_Note._--Before transferring to either kinds of canvas or wood panel
in cold weather, it is absolutely necessary to thoroughly warm the
final support, otherwise the gelatine solution will gelatinize
before the excess can be removed from between the surfaces.
THE SINGLE TRANSFER PROCESS.
The single transfer process may be briefly described as
follows:--The sensitive tissue is exposed under a negative and the
exposure gauged by actinometer as for double transfer printing.
After removal from the pressure frame the printed tissue is plunged
into clean cold water along with a piece of transfer paper of any
desired surface or quality, cut a little larger than the tissue (to
provide a margin by which the picture may be handled without injury
during development). After soaking the requisite time, the two
prepared surfaces are brought into contact under the water, removed
to a squeegeeing board, plate of glass or zinc, and squeegeed into
contact; care must be taken to use only as much pressure as is
needed to remove the superfluous water from between the surfaces. A
sponge may be used instead of a squeegee, or both may be dispensed
with, if care is taken to remove every trace of air from surfaces
before lifting from the cold water bath. When neither squeegee or
substitute for it is used, the print must be handled with greater
care, as undue bending before atmospheric pressure comes into
operation would destroy contact. The print is hung up to drain, and
more time allowed between mounting and development. Development is
the same as in double transfer, with one or two rather important
exceptions. 1st. The single transfer print is developed upon the
material on which it is to remain. 2nd. There is no preparation of
the supports, neither in the case of paper or opal. 3rd. The
developed print can be soaked for a considerable time in a saturated
solution of alum without injury, the alum solution greatly assisting
in removing bichromate.
CARBON TRANSPARENCIES.
Carbon transparencies, either for projection, enlargement, or
reproduction, are printed in a special tissue known as transparency
tissue, and developed on glass plates prepared with a thin coating
of fine hard gelatine. The coating solution is composed as
follows:--
Gelatine 3/4 oz.
Water 40 "
Bichromate potash 1 dram.
The glass plates are carefully selected, free from bells, scratches,
and other defects; thoroughly cleaned, either by acid or rubbing
with plate powder to remove every trace of grease, and then coated
with the gelatine solution, and placed in a rack to dry; when dry,
exposed to light to render the film somewhat insoluble. It is not
desirable to print until the film is absolutely hardened throughout.
The print adheres firmly to the plate when the substratum is not
over-printed.
A positive intended for projection should show clear glass in the
highest lights without undue density in the shadows, all details
plainly seen--in a word, quite transparent.
Positives intended for enlargement must be fully exposed--that is to
say, every detail on the highest lights brought out, but no more;
beyond that point there is nothing to be gained. Over-printing in
the transparency tends to bury detail in the shadows of the enlarged
negative, and to blend the highest grades in the high-lights,
reducing the roundness or modelling of the picture.
In the case of very hard negatives intended for enlargement, the
usual treatment is to sun the whole surface of the transparency in
order to secure detail in the high-lights. A moment's consideration
will convince any practical printer that nothing but injury to the
final print can result from such treatment of the transparency. The
high-lights are degraded, the details in the shadows further buried.
The better method is to make an extra special transparency tissue,
for the printing of such hard negatives, containing a greatly
reduced proportion of pigment to gelatine. Such a tissue permits
greater depth of printing, retains all details in the shadows and
high-lights, and, in fact, enables the enlarger to produce a
negative that will yield a thoroughly satisfactory print.
REPRODUCED NEGATIVES.
In making reproduced negatives from hard originals, ordinary
transparency tissue will serve every purpose. The transparency is
printed in the usual way, and developed on a prepared glass plate;
when dry a negative is printed from the transparency without special
treatment and also developed on glass, when a decided reduction of
density will be found to have taken place. The reproduced negative
will possess all the good qualities of the original, plus improved
printing quality. It is only in the case of extremely hard negatives
that the extra special tissue is required.
If a perfect reproduction of an original negative is required, the
transparency must be printed either in very weak light or in direct
sunlight. Either method gives a brighter image than that produced in
ordinary diffused daylight. The same method must be adopted in
printing the negative.
_Note._--Care must be taken when direct sunlight is used to see that
the pressure frame and everything in and about it is thoroughly dry,
otherwise the tissue may stick to the negative, spoiling the print
and probably the negative also. It must also be noted that two
tints, printed in direct sunlight, although of apparently the same
depth, mean quite as much as three such tints printed in diffused
light.
FAILURES AND DEFECTS: THEIR CAUSES AND CURE.
As a rule, failures in working the carbon process are caused, as in
most other cases of failure, by imperfect _knowledge of the
substances and nature of the ingredients used in the process_.
Before going into further detail, it may be as well to point out
that a great deal of misunderstanding has been caused, by writers on
this subject--that may be fairly termed "blind leaders of the
blind." With only slight knowledge of the subject they have misled
beginners by assuring them that the process is simplicity itself, in
fact the most simple photographic printing process extant. Up to a
certain point, and to that certain point only, is such description
true. There are no subtle chemical combinations, no mixing and
maturing of toning or other solutions. But--and in this case there
is great virtue in the _but_--the greatest care is not only
required, it is absolutely demanded, in manipulation. A carbon print
from start to finish is probably subject to more chances of injury
than any other form of print in existence. When this fact has been
fully grasped by the novice, and he has been thoroughly prepared for
the difficulties before him, the rest is plain sailing. Care, and
care only; nothing beyond. He who wishes to succeed in carbon work
must pay infinite attention to every small matter of detail as far
as such detail relates to manipulation, otherwise he will only
succeed in achieving failure.
FRILLING AND RETICULATIONS.
Frilly reticulations are generally caused by over-soaking the tissue
before development, or failing to provide protection of the clear
portions of the margin of the negative by a safe edge.
SPOTS ON THE FINISHED PRINT.
Spots are generally caused by solid particles of grit or other
impurities being allowed to find their way into the water in the
process of development, or, as in the case of certain peculiar
circular spots that often deface the carbon print, such spots are
caused by small fragments of tissue broken from the edges in
cutting, which, being of the same colour as the prepared surface of
the tissue and exceedingly small, often escape notice. They adhere
most tenaciously to the surface of the tissue, and if not removed
before the print is mounted upon its temporary or final support,
cause the mischief referred to; being confined between two surfaces
they cannot escape, but are dissolved by the water used in
developing the print, swell and make a circular patch, often greatly
injuring the picture.
Spots of a different character are produced in quite an opposite
direction. Instead of being black they are light, in groups each
spot having a dark rim on the outside. They generally occur in
under-exposed prints, and are formed by fine particles of air
imprisoned between the coating of gelatine and the paper support.
When the tissue is mounted for development and placed in warm water,
the fine particles of air swell, and not being able to escape from
between the surfaces, impress themselves into the yielding portions
of the printed tissue and make the marks above referred to, unless
the printing has been deep enough to allow of their removal before
development is completed.
CAUSE OF FAILURES IN THE SECOND TRANSFER.
Other causes of failure refer particularly to prints by double
transfer, either to paper, opal, ivory, canvas or wood panel or any
similar surfaces.
Such failures are generally produced by _soap_, _fat_, or _any kind_
of greasy substances being permitted to find their way into the
water in which such prints have been manipulated previous to their
final transfer. Another point should be mentioned: the sooner a
print intended for second transfer is finished the better the result
will be.
PRESSURE MARKS.
Pressure marks are caused by using damp tissue or damp pads in the
pressure frame. It is recommended that a piece of waterproof
material, such as mackintosh cloth, be placed between the tissue and
the padding, and that the pads be as smooth and free from grain as
possible. It will be found on close examination that the mottled,
spotty appearance, known as pressure marks, closely resemble the
texture of the pads behind the tissue.
_Thos. S. Skelton._
INDEX.
=A.=
Alpine Photography, 9
" Outfit for, 9
" Lens for, 10
" Carrying camera in, 12
" Plates for, 14
" Carrying Baggage for, 15
" Outfit for Developing, 16
" Exposures, 17
" Development, 18
" " Formulæ, 20
" Light (tables), 21, 22
Accelerator, 24
Alum Bath, Formula, 41
Aberration, Spherical, 60
" Chromatic, 61
Astigmatism, 62
Aplanat Lens, 64
Astigmat Lens, 64
Aperture of Lens, 68
Angle of Image, 70
Accessories in Portraiture, 79
Architectural Photography, 117
" " Camera for, 118
" " Lenses for, 119
" " Plates for, 122
Actinometer for Platinotype, 208
" for Carbon Process, 271
=B.=
Backing Mixtures, 49
Background in Portraiture, 78
Breadth in Pictorial Work, 93
Blisters on P.O.P, 194
Bromide Printing, 225
" Safe light for, 226
" Negative for, 227
Bromide Paper, sensitive side of, 227
" Printing, 232, 233, 227
" " Lamp for, 228
Bromide Printing, masks and discs, 230
" " Vignetting, 231
" " Cloud Printing, 231
Bromide Paper, development of., 233
" " Iron developer for, 234
" " Metol, 235
" " Hydrokinone for, 236
" " Eikonogen for, 236
" " Clearing Bath, 235
" " Fixing Bath, 235
Bromide Prints, toning with gold, 237
" " Toning with Uranium, 238
" " Intensifying, 238
" " Reducing, 239
" " Cheap Trays for, 240
=C.=
Camera, Carrying in Alps, 12
Caramel for Backing, 49
Curvature of Field of Lens, 62
Cooke Lens, 65
Composition in Pictorial Work, 95
Clearing Bath for Platinotype, 203, 218
Cloud Printing on Bromide Paper, 231
Clearing Bath for Bromides, 235
Clearing Bath for Gum-Print, 251
Carbon Process, outline of, 253
" Safe Edge for, 269, 255
" Carbon Process, Negative for, 255
" Transfer Paper for, 266, 256
" Temporary Support, 258
" in Detail, 261
" Squeegee for, 263
" Stock Jelly, 263
" Coating Paper for, 264
" Transfer Papers for, 266
" Flexible Support, 267
" Sensitizing Tissue for, 267
" Drying Tissue, 267
" Negative for, 268
" Reasons for Transfer, 269
" Transfer to Opal, 271
" Actinometer, 271
" Exposure, 272
" Transfer from Opal, 272
" T'sfer. from Flex. Spt., 274
" Glazed Surface Prints, 275
" Transfer to Ivory, 276
" Transfer to Canvas, 276
" Preparation of Canvas, 277
" " Linen, 278
" " Wood, 279
" Single Transfer, 289
" Transparencies by, 280
" Reproduced Negs. by, 281
" Failures and Defects, 282
" Frilling of Print, 283
" Spots, etc, 283
" Pressure Marks, 284
Canvas, Carbon Prints on., 276
=D.=
Development, 23
" Dishes for, 25
" Effect of Temperature on, 28
" Light for Developing Room, 28
" with Pyro-Ammonia, 29
" " Formulæ, 30
" with Pyro-Soda, 33
" " Formulæ, 34
" with Ortol, Formulæ, 35
" with Hydroquinone (Quinol), 36
" " Formulæ, 36
" with Ferrous Oxalate, 36
" " Formulæ, 37
Drying Plates, 41
Dark Room Light, Testing, 44
Defects of Negative, 43
Dallmeyer's Portrait Lens, 64
" Stigmatic Lens, 65
Depth of Definition (Focus), 71
Distortion of Lens, 72
Development of Portrait Negative, 81
" " Formulæ, 83
Detail in Pictorial Work, 110, 93
Development in Hand Cam. Exps., 137
" Formulæ, 138
" of Lantern slides, 149, 147
" of Enlargements, 168
" of P.O.P, 188
" Platinotype Paper, 221, 204
" of Bromide Paper, 234-6, 233
" of Gum Print, 250
=E.=
Exposure, Over, 27, 32
" Under, 27, 32
" Table with Pinhole, 76
Exposure of Lantern Slides, 146
Enlargements, 155
" Light for, 156, 162
" Daylight, 156
" Apparatus for, 157
" Lens, 164
" Direct, 167
" Development of, 168
Enlarged Negatives, 171
" " Transparency for, 172
Exposure in Carbon Printing, 272
=F.=
Fixing, 37
" Formula, 38
Frilling, 41
Flat Image, 44
Fog on Negative, 44
Fog-Green, 45
Focal Length of Lens, 66
" " Comparison of, 67
Focussing Interiors, 127
Finders for Hand Cameras, 134
Focussing Scale for Hand Camera, 135
Fixing Bath for Bromide, 235
Frilling of Carbon Print, 283
Failures in Carbon Printing, 282
Flexible Suppt. Carbon Process, 267, 274
FORMULÆ:--
Development, Pyro-amm. (Abney), 20
" " (Bothamly), 30
" Pyro-soda " , 34
" Ortol " , 35
" Hydrokinone " , 36
" Ferrous Oxalate " , 37
Fixing, Hypo " , 38
Clearing, Alum " , 41
Reduction, Ferricyanide " , 50
Belitzski Reducer " , 51
Intensification, Mercury " , 52
" Uranium " , 54
Development, Metol (Baker), 83
" Pyro-Soda " , 83
" Quinol and Rodinal " , 83
" Amidol (Thomas), 138
" Hydrokinone " , 138
" Eikonogen " , 138
" Metol (Pringle), 150
" Ortol " , 151
" Hydrokinone " , 151
" Amidol (Hodges), 169
Fixing, Hypo " , 171
P.O.P. Toning, Gold (Lambert), 180, 181, 182
" Alum Bath " , 184
" Combined Bath (gold) " , 184
" " (lead) " , 184
" " (gold) " , 185
P.O.P. Glazing " , 186
" Mounting " , 187
" Development, Quinol ", 188
" Toning, Platinum " , 190
" Fixing " , 191
" Toning (gold) " , 191
" Reducing " , 192
" Tinting " , 194
Platinotype Clearing (Hinton), 203
" Developing " , 202, 214
" Toning " , 223
Bromide Develping., Iron, (Henry), 234
" Clearing " , 235
" Fixing (Henry), 235
" Developing, Metol " , 235
" Quinol & Eikonogen " , 236
" Toning (gold) " , 237
" Reducing " , 238, 239
Carbon Process Waxing, (Skelton), 259
" " Tissue Jelly " , 263
" " Waxing " , 274
" " Collodion " , 276
" " Substratum " , 276, 278, 279, 280
=G.=
Green Fog, 45
" " Cure for, 46
Glazing P.O.P., 185, 186
Gum Bichromate Process, 241
" " Paper for, 243
" " Outline of Process, 245
" " Gum Solution, 246
" " Colours, 246
" " Brushes for, 247
" " Development, 250
" " Clearing Bath, 251
=H.=
Hypo.--Test for, 40
Hard Image, 44
Halation, 48
Head-rest in Portraiture, 78
Hand Camera, Photography with, 131
" " Lens for, 133
" " Finders for, 134
" " Shutter for, 134
" " Focussing Scale for, 135
" " Development of Exposures, 137
Hardening P.O.P., 195
=I.=
Intensification of Negatives, 51
" with Mercury formulæ, 51
" with Uranium formulæ, 53
Image Formation, 58
Image Angle, 70
Isochromatic Plates for Pict. Work, 115
Interior--Focussing, 127
" Exposure for, 127
Intensification of Lantern Slides, 153
" of P.O.P., 191
Intensifying Bromide Prints, 238
Ivory, Carbon Prints on, 276
=J.=
Jena Glass for Lenses, 64
=L.=
Latent Image, 23
Local Development, 20, 32
Lens, 57
" Function of a, 59
" Aberrations of a, 60
Lenses, Comparison of, 73
" Testing, 73
Lens for Pictorial Work, 113
" for Architectural Work, 120
Levels " " " , 121
Lens for Hand Camera, 133
Lantern Slides, 141
" " Various Processes, 143
" " Camera for Making, 144
" " Exposure of, 146
" " Development, 147, 149
" " Warm Tones on, 148, 152
" " Reducer for, 153
" " Intensifier for, 153
Linen, Prints on by Carbon Process, 278
=M.=
Mountain Photography see Alpine do.
Monocles, 75
Moving Objects & Architectl. Work, 129
Mounting P.O.P., 187
=N.=
Negative Making, 23
" Washing, 39
" Drying, 40
" Defects of the, 43
" too Thin, 43
" too Dense, 43
" Image too Flat, 44
" Image too Dense, 44
" Fog on, 44
" Green Fog on, 45
" Black Spots, Marks, Bands on, 46
" Transpnt. Bands, Spots on, 47
" Stains on, 47
" to Intensify, 51
" to Reduce, 49
" to Varnish, 54
" for Platinotype, 222
" for Bromide Printing, 227
" Reprodn. by Carbon Process, 281
" for Carbon Printing, 268, 255
=O.=
Optics--see Lenses, 57
Opal for Carbon Print, 272, 271
=P.=
Preservative, 25
Pinhole Image, 75, 58
Portrait Lens, 64, 63
Planar Lens of Zeiss, 65
Pinhole Table of Exposures, 75
Portraiture, 77
" Shutter for, 77
" in Ordinary Rooms, 79
Portraits Out-of-Doors, 80
Portraiture, Lenses for, 80
" Development in, 81
" " Formulæ, 83
Pictorial Photography, 87
Plates for Architectural Work, 122
P.O.P., Print-out Paper, 177
" Care of the Paper, 178
" Printing, 178
" Washing, 179
" Toning, 180
" Fixing, 183
" Combined Bath for, 184
" Alum Bath for, 184
" Drying, 185
" Glazing, 186, 185
" Matt Surface, 185
" Mounting, 187
" Development of, 188
" Platinum Toning, 189
" Toning with Gold & Platnm., 191
" Intensifying, 191
" Reducing, 192
" Defects of, 193
" Stains on, 195, 193
" Blisters, 194
" Tinting, 194
" Hardening, 195
" Spots on, 195
Printing P.O.P., 178
Platinotype Printing, 197
" Paper to Preserve, 199
" Outline of Process, 201
" Development, 220, 204
" Exposure of, 206, 202
" with Act'meter, 207
" Temperature of Develmt., 212
" Developing Salts, 213
" Papers, various kinds, 214
" Sepia Paper, 215
" Clearing Bath, 203, 218
" Devpmt. by Glyc. method, 221
" Negative for, 222
" Prints Toning, 223
Printing Bromide Paper, 232, 233, 227
Papers for Gum-Bichro. Process, 243
Pressure Marks in Carbon Prints, 284
=R.=
Restrainer or Retarder, 24
Reducer, 24
Reduction of negative, 49
" Formulæ, 50, 51
Reduction, local, 50
Refraction of Light, 60
Rapid Rectilinear, Symmetrical, Lens, 64
Rapidity of Lens, 68
Rembrandt Effects in Portraiture, 79
Retouching Portrait Negative, 83
Reducer for Lantern Slides, 153
Reducing P.O.P., 192
Reducing Bromide Prints, 239
Reticulation of Carbon Prints, 283
Reproduction of Neg. by Car. Pro., 281
=S.=
Satz-Anastigmat Lens, 65
Stigmatic Lens of Dallmeyer, 69
Stops, Value of, 69
Stops, Comparative Value, Table, 70
Spectacle Lens, 75
Selection in Pictorial Work, 95
Shutter for Hand Camera, 134
Stains on P.O.P., 193, 195
Sepia Platinotype, 215
Spots on Carbon Prints, 283
Single Transfer Carbon Process, 289
Safe Edge for Carbon Printing, 255, 269
Sensitizing Carbon Tissue, 267
=T.=
Tripod on Ice, a caution, 14
Test for Hypo, 40
Testing Dark-room Light, 44
Tele-photo Lens, 70
Truth in Pictorial Photograph, 91
Tone Value, 107
Toning P.O.P., 180, 189, 191
Tinting P.O.P., 194
Toning Platinotypes, 223, 224
Toning Bromide Prints (gold), 237
" (uranium) 238
Trays for Bromide Printing, 240
Transparency by Carbon Process, 280
T'sfer. Paper for Carbon P'cess., 256, 266
Temporary Support, Carbon Process, 258
TABLES:--
Light, 21, 22
Stops,70
Pinholes, 75
=V.=
View Finder, 13
Varnishing Negatives, 54
Vignetting Bromide Prints, 231
=W.=
Washing Plates after Development, 38
Wood, Carbon Prints on, 279
=Z.=
Zeiss-Planar Lens, 65
" Lens for Architecture, 120
* * * * * * * * *
END OF WORK
* * * * * * * * *
ADVERTISEMENT
* * * * * * * * *
TWELVE ...
PERFECT PRODUCTIONS.
_BARNET_
|
+---------- _Ordinary_ = = Plates
|
+---------- _Studio_ "
|
+---------- _Extra Rapid_ "
|
+---------- _Rocket_ "
|
+---------- _Lantern_ "
|
+---------- _Photo-Mechanical_ "
|
+---------- _Astronomical_ "
|
+---------- _Platino-Matt_ Bromide Paper
|
+---------- _Ordinary Bromide Paper_
|
+---------- _Snow Enamel Paper_
|
+---------- _P.O.P._
|
+---------- _Carbon Tissue_
Price List on application.
Manufactured by
ELLIOTT & SON,
... BARNET.
* * * * * * * * *
Transcription Notes:
The original spelling and grammar have been retained. Footnotes have
been moved to the end of the paragraphs in which they are referenced.
Minor adjustments to hyphenation and other punctuation have been made
without annotation. The caret symbol ^ is used to represent a number
or expression raised to some power (5^2=25).
Typographical changes to the original work are as follows:
pg 10 kodak/Kodak: a form of ...
pg 15 removed repeated word at: can be got at ...
pg 62 simultaneouly/simultaneously: where they cross ...
pg 81 two/too: too far behind or ...
pg 95 frolicing/frolicking: joyous sunshine ...
pg 108 rythmical/rhythmical: something ...
pg 144 salutory/salutary: has a very ...
pg 145 concatention/concatenation: under any ...
pg 153 potass/potash: metabisulphite of ...
pg 193 power/powder: ("bleaching ...
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